bootparam 中文man页面

NAME

bootparam - 介绍Linux核心的启动参数  

描叙

Linux 核心在启动的时候可以接受指定的"命令行参数"或"启动参数"．在通常情况下，由于核心有可能无法识别某些硬件，或可能将某些硬件识别为不正确的配置，因此，这些参数可以被用来提供正确的硬件配置参数。当Linux核心被BIOS直接启动的时候（比如说你的核心是从使用了 "cp zImage /dev/fd0" 命令制造的 Linux 启动软盘来启动的），你无法指定任何的启动参数。因此，为了能够指定启动参数，你必须使用某些能够传递启动参数的软件，例如 LILO 或 Loadlin。为了使用很少的参数来改变的核心配置，可以使用 rdev，查看 rdev（8） 可以得到更多的细节。

由 Werner Almesberger 开发的 LILO 程序 (LInux LOader) 是最普遍的启动配置软件。它能够启动各种不同的系统核心，这些启动配置信息被放置在一个简单明了的文本文件中（请看 lilo（8） 和 lilo.conf(5).）

LILO 可以启动象 DOS，OS/2，Linux，FreeBSD，UnixWare 这样的操作系统，而且灵活性也非常强。

另外一个较为普遍的启动软件是"LoadLin"。这是一个基于 DOS 操作系统的软件。该软件能够从DOS提示符下启动Linux核心（使用启动参数），只要某些必需的资源可用就行。这对于那些希望从 DOS 系统中启动 Linux 的人来说是很不错的方法。

如果你的硬件能够被 DOS 驱动程序启用的话，LoadLin也会是非常有用的。一个最常见的例子是设置与 SoundBlaster 兼容的声卡。这些声卡通过使用 DOS 驱动程序设定一些寄存器就可以将它们设置成为 SB 兼容模式的声卡。在DOS下启动这些声卡的启动程序，然后使用LoadLin程序启动Linux，这样就可以避免由于重新启动Linux系统而造成声卡被重新设置。

参数列表

核心参数行被解析成为一个由空格分隔的字符串列表（即启动参数表）。大部分的启动参数的格式就象下面这样

名字[=值1]，[值2]……[，值10]

其中"名字"是一个唯一关键字，被用来区分接受值（如果有的话）那一部分核心。要注意的是 10 个值的限制是确实存在的，目前的程序代码只能对每个关键字处理 10 个逗号分隔的参数（当然，在一些复杂的应用中，你可以通过重新使用同样的关键字来传递多于10个的参数，只要配置程序可以支持该方法）

大部分的排序工作是在 linux/init/main.c 中进行的。首先，核心检查参数是否为 "root="、"nfsroot="、"nfsaddrs="、"ro"、"rw"、"debug" 和"init"这些特殊参数中的一种。这些参数的意义我们将在下面说明。

然后，核心会搜索"配置程序队列"（bootsetups队列）来查看指定的参数字符串（比如"foo"）是不是与某个配置指定设备或是核心的配置程序建立了关联。例如假设你传递给核心 foo=3,4,5,6，那么核心会搜索 bootsetups 队列看看"foo"是否已经注册。如果是，那么核心将运行与"foo"关联的配置程序（比如foo_setup()）并且将参数3，4，5，6交给核心命令列。

任何象 "foo=bar" 这样格式的参数不会被上面所说的那样，作为一个配置程序的关联被接受，而是被解释成为一个环境变量的设置。一个（无用的？）例子就是使用 "TERM=vt100" 作为核心的启动参数。

任何既不被核心接受又不被解释为环境变量的参数会被传送给第一个系统进程，通常这会是init程序。最常用的传递给 init 进程的参数是 "single"，它告诉init使用单用户模式启动计算机，并且不要执行任何的守护进程。查阅帮助，看看你所装版本的 init 程序可以支持的参数。

一般的、与设备无关的启动参数

`init=...'

这个启动参数提供核心执行时的初始化命令。如果它没有被设置，或者没有被找到的话，核心会去尝试调用 /etc/init, 然后是 /bin/init, 然后是 /sbin/init, 最后是 /bin/sh ，如果都失败了，就会提示一个异常信息。  

`nfsaddrs=...'

该启动参数设置 nfs（网络文件系统）启动地址为指定的字符串值。该启动地址被用于网络启动中。

`nfsroot=...'

该动参数设置 nfs（网络文件系统）根目录名为指定字符串。如果该字符串不是以'/'、','或者一个数字开始的，则该字符串加上"/tftpboot/"的前缀。

`no387'

(只有当CONFIG_BUGi386被定义后才有效) 某些 i387 协处理器在使用 32 位保护模式时会出现错误。例如，一些早期的ULSI-387芯片在处理浮点运算时会出现死锁的情况。使用"no387"启动参数可以让Linux忽略你的算术协处理器的存在。当然，这时你就必须将你的核心编译成为支持数学仿真模式。

`no-hlt'

(只有当CONFIG_BUGi386被定义后才有效) 某些早期的 i486DX-100 的处理器芯片在使用 "halt" 时会出现问题，使用这个指令后它不会正常的返回到操作模式。使用 "no-halt" 指令告诉 Linux 在没有事情可做的时候，只是执行一个无限的循环指令，而不是让CPU进入"halt"模式。这样就可以令人们使用这些有缺陷的芯片来运行 Linux。

`root=...'

这个参数告诉核心在启动的时候使用哪个设备被作为根文件系统。其缺省值是你在编译核心的时候就所确定的根设备。如果你想要修改该值，比如说，将第二个软盘驱动器作为根设备，你可以使用 "root=/dev/fd1" （根设备也可以用 rdev(8)）； 来设置。

根设备能够以符号形式或数字形式来指定。一种符号指定形式是 /dev/XXYN，其中 XX 代表设备类型（ "hd" 代表普通 IDE 硬盘，紧跟其后的 Y 的范围是 "a" 到 "d"； "SD" 代表 SCSI 硬盘，紧跟其后的 Y 的范围是 "a" 到 "e"；"ad" 代表 Atari ACSI磁盘，紧跟其后的 Y 的范围是 "a" 到 "e"；"ez" 代表 Syquest EZ135 兼容的使用并口的可移动硬盘，紧跟其后的 Y 的值只能是"a"；"xd" 代表 XT 兼容的磁盘，紧跟其后的 Y 的值是 "a" 或者是 "b"；"fd" 代表软驱，而 Y 代表软驱的序号 - fd0 代表 DOS 的 "A："， fd1代表DOS的 "B："），Y 表示驱动器字母或序号。N 代表驱动器的分区号（以十进制数值表示，当然，软驱是没有该信息的）。目前的核心可以使用更多的驱动设备，比如 nfs，ram，scd，mcd，cdu535，aztcd，cm206cd，gscd，sbpcd，sonycd，bpcd，其中大部分都是 CD-ROM 设备。（nfs 指示网络启动的位置；ram 表示一个 ram 虚拟磁盘（ram 表示可读写储存器）。

需要注意的是以上这些指定对你文件系统上的设备名称并没有做任何实质改变， "/dev/" 部分的描述只是出于传统习惯。

你也可以通过使用数字形式的主/次设备号指定根设备，但这是很笨拙和不方便的方法。（例如，/dev/sda3 的主设备号是 8，次设备号是 3，所以你也可以使用 "root=0x0803" 来指定根设备。）

`ro'和`rw'

"ro" 选项告诉核心使用"只读"方式装配文件系统。这样可以让"文件一致性检查"程序（fsck程序，用来检查磁盘的工具，类似 DOS 的 scandisk 程序）能够在一种所谓"静止" （也就是说没有任何对文件系统的写操作）的文件系统中执行。需要进行写操作的进程必须等到该文件系统使用 "读/写"方式重新装配以后才能进行，例如，使用了"mount -w -n -o remount /"命令。（请查看 mount(8)。)

"rw" 选项告诉核心使用"可读写"方式装配文件系统。这是缺省值。

只读方式和可读写方式的选择可以使用 rdev(8). 来设定。

`reserve=...'

该参数用来设定保留区域，使得该区域的 I/O 端口不会被检测。该命令的格式是

reserve=iobase,extent[,iobase,extent]...

在某些情况下你的机器也许必须避免设备驱动程序检测（自动检测）某些指定区域的设备。这些情况有可能是因为由于检测会导致硬件错误，或者硬件会被错误地识别，又或者你只是不想核心对该硬件进行初始化。

reserve(保留)启动参数指定一个不要检测的 I/O 端口保留区。设备驱动程序不会检测保留区域的 I/O 端口，除非其他的启动参数明确的指定需要去检测。

例如，命令行

reserve=0x300,32 blah=0x300

表示设置保留 I/O 区域 0x300 到 0x31f（共32个端口）不会被 `blah' 程序以外的驱动程序所检测。

`mem=...'

PC 规范定义的返回内存数的 BIOS 调用最大可以返回 64MB 内存。 Linux 使用这个 BIOS 调用检测机器安装了多少内存。如果你拥有超过 64MB 的内存，就可以使用这个参数告诉 Linux 你的内存数。该值可以是 10 进制的或者是 16 进制的（加上 0x 的前缀），后缀也可以加上 "k" （乘以 1024）或 "M" （乘以 1048576）。下面是 Linux 初始人 Linus 对 "mem=" 参数使用的声明： "核心能够接受任何你给予的 'mem=xx' 参数，但是如果你欺骗它的话，它迟早会让你死的很难看。参数用来指定最高位的 RAM 地址，所以 'mem=0x1000000' 表示你拥有 16MB 的内存。而对于96MB内存的机器来说你应该设置为 'mem=0x6000000'。

注意注意注意：有些机器可能会将内存高端设置为 BIOS 所使用，所以你可能将不能全部拥有 96MB 地址空间。反之，有些芯片可以将包括 BIOS 的物理内存影射到内存高端去，所以，你可以用的实际空间可能会是 96MB+384kB。但是如果你告诉 Linux 核心你拥有的内存超出你的实际内存的话，将会发生很糟糕的事情。也许躲得过初一，躲不过十五。"

`panic=N'

在缺省情况下，核心并不会在异常后重新启动系统，但是这个参数可以指定内核在发生异常后 N 秒后重新启动（如果 N>0）。这个异常时限也可以使用 "echo N>/proc/sys/kernel/panic" 来设定。

`reboot=[warm|cold][,[bios|hard]]'

（只有当 CONFIG_BUGi386 被定义的时候该参数才起作用）从 2.0.22 版本后的核心开始，reboot 命令在缺省情况下使用冷启动。你可以使用 "reboot=warm" 来进行老版本所的缺省的热启动方式。（冷启动意味着对所有的硬件设备进行重新设置，但是也有可能令在磁盘缓冲区中尚未写到磁盘上的数据被破坏。热启动的优点是速度比较快。）在缺省情况下，要求键盘控制器向机器发出可以重新启动的低电位脉冲是很困难的，但是至少有一种类型的主板不会这样工作。选项 "reboot=bios" 将用 BIOS 的设置代替跳线。

`nosmp' 和 `maxcpus=N'

（该参数只有当 __SMP__ 参数被定义的时候才有效）命令行选项 "nosmp" 或 "maxcpus=0" 将会禁止激活 SMP（对称多处理）功能，选项 "maxcpus=N" 限制在 SMP 方式下工作的 CPU 最大数目为 N．

核心开发者所使用的启动参数

`debug'

核心信息被传递给核心的日志守护进程 klogd 使得它们能够被记录在磁盘中。优先级高于 console_loglevel 的信息也可以在控制台上被显示出来。（如果想了解信息优先级，可以去查看<linux/kernel.h>文件。）在缺省情况下，所有比调试信息级别高的信息都会被写入日志文件。但是这个启动参数的设置，可以使得核心将 DEBUG（调试信息）级别的信息写到日志里。 console loglevel 也能够在系统运行时通过使用 klogd 来设置。请看 klogd(8).

`profile=N'

用来激活一个核心记录程序。如果你需要了解核心在什么地方消耗其CPU周期，可以通过设置 prof_shift 为一个非零值来激活核心记录程序。可以通过在编译内核的时候指定 CONFIG_PROFILE 值也可以通过 "profile=" 选项来指定 prof_shift 的值。当 prof_shift 通过以上方式指定为 N，或通过 CONFIG_PROFILE_SHIT 的方式指定，或者直接使用其缺省值 2 的时候，这个值表示记录程序使用 prof_shift 个时间间隔进行记录：每个时间间隔是一个时钟滴答。当系统执行核心代码的时候，一个记数器的值会不断的增加。

profile[address >> prof_shift]++;

原始的配置文件可以从 /proc/profile. 中读到。或者你也可以使用象 readprofile.c 之类的工具来阅读配置文件。任何写到 /proc/profile 中的操作将清除记数器。

`swap=N1,N2,N3,N4,N5,N6,N7,N8'

设置控制核心的虚拟存储交换算法的 8 个参数。这8个参数是 max_page_age, page_advance, page_decline, page_initial_age, age_cluster_fract, age_cluster_min, pageout_weight, bufferout_weight。只能用于核心控制。

`buff=N1,N2,N3,N4,N5,N6'

设置核心缓存管理的 6 个参数，分别是 max_buff_age, buff_advance, buff_decline, buff_initial_age, bufferout_weight, buffermem_grace。同样也只能用于核心控制

使用内存虚拟磁盘的启动参数

（该参数只在核心使用 CONFIG_BLK_DEV_RAM 进行编译后才有效）在通常情况下，在 Linux 下使用一个内存虚拟磁盘（RAMDISK）并不是一个好的方法 - 因为系统会自动、高效的使用可用的内存。但是当用软盘启动的时候（或者当建立一个启动软盘的时候），将软盘的内容读到一个内存虚拟磁盘中是非常有用的。另外的情况也有可能是有一些模块（或者是文件系统又或者是硬件的）必须在主磁盘被访问前被调到内存中来。

在 1.3.48 版本的 Linux 中，ramdisk 的操作被彻底的改变了。在 1.3.48 以前的版本中，内存是静态分配的，"ramdisk = N" 参数提供内存的大小。（这些也能够在核心被编译的时候被设置，或者也可以使用 rdev(8).来进行设置） 从 1.3.48 开始，内存虚拟磁盘开始使用高速缓存，而且可以动态的增加其空间。如果需要了解有关最新的内存虚拟磁盘设置（比如你要了解怎么使用 rdev(8) 来进行ramdisk的设置）请查看 /usr/src/linux/Documentation/ramdisk.txt.

有关的参数一共有四个，两个是布尔变量，两个是整型值。

`load_ramdisk=N'

如果 N=1，载入一个内存虚拟磁盘。如果 N=0，不载入内存虚拟磁盘（这是缺省值）。

`prompt_ramdisk=N'

如果 N=1，需要提示插入软盘。（这是缺省值）如果 N=0，没有提示。（因此，这个参数永远也不会需要）

`ramdisk_size=N' 或者 `ramdisk=N'

设置内存虚拟磁盘的最大空间为 N kB。缺省值是 4096 kB (4MB)。

`ramdisk_start=N'

设置启动块数值（也就是内存虚拟磁盘从软盘的多少偏移量位置开始）为 N。由于紧跟在内存虚拟磁盘后面的是核心映象文件，所以这个设置是必要的。

`noinitrd'

（只有核心在编译时使用了 CONFIG_BLK_DEV_RAM 标志和 CONFIG_BLK_DEV_INITRD 标志时才会有效）目前，我们基本上可以通过编译核心使其支持使用初始化内存虚拟磁盘（initrd:Initial Ramdisk）。当启用 initrd 的时候，启动进程会载入核心和一个已经初始化的内存虚拟磁盘，然后核心会将 initrd 转变为一个"普通的"内存虚拟磁盘，并将它激活为可读写的根设备。接下来，会被执行 /linuxrc， "真正的"根文件系统被激活，而 initrd 文件系统则被转移到 /initrd 目录下。最后顺序执行正常的启动程序（比如说是 /sbin/init 程序）。如果希望得到关于 initrd 的详细的介绍，可以参考 /usr/src/linux/Documentation/initrd.txt．

自然，'noinitrd' 参数告诉核心，尽管核心是按照使用 initrd 的参数来编译的，但是也不需要使用我们上面描述的过程。但是，仍然保留 initrd 的所有数据到 /dev/initrd. 目录下。（该设备只能被使用一次，数据在最后一个使用 initrd 的进程被关闭后会释放掉） /dev/initrd．）

SCSI设备启动参数

关于这个区域的一些符号说明：

iobase 第一个SCSI主设备占用的I/O端口。它用 16 进制的数据指定，一般介于 0x200 到 0x3ff 之间。

irq SCSI 卡设置的硬件中断号。具体的值取决于 SCSI 卡的具体要求，一般使用的中断号是 5，7，9，10，11，12 和 15。其他的中断号一般会被一些外设所占用，比如说，IDE 接口的硬盘，软盘驱动器，串口等等。

scsi-id SCSI 适配器在 SCSI 总线上使用的用来标识自身的识别号码（ID）。只有一部分 SCSI 适配器允许你改动该 ID 的值，大部分都是被固化好的。缺省值一般是 7，可是，在 Seagate 和Future Domain TMC-950 的板卡上是 6。

parity 是否允许 SCSI 适配器在交换数据的时候使用奇偶效验。指定一个非零值，奇偶效验会起用，如果指定为零则不会启动奇偶效验。同样，不是所有的 SCSI 适配卡支持选择奇偶效验的启动参数。

`max_scsi_luns=...'

一个 SCSI 设备能够使用一些包括它自己在内的"子设备"。最常用的例子是现在的 SCSI CD-ROM 设备能够同时处理多张光盘。每张光盘使用"逻辑单元号码"(LUN)来确定其位置。当然，大部分设备，比如硬盘，磁带机都只能处理一个设备，因此它们的 LUN 会被设置为 0 一些设计上有缺陷的 SCSI 设备一旦发现 LUN 号码不为零时，就可能不再继续工作。因此，如果在编译的时候没有设置 CONFIG_SCSI_MULTI_LUN 标志，新的核心将使用 0 作为缺省值。

如果需要在启动的时候指定 LUN 的值，可以使用 "max_scsi_luns=n" 作为启动参数，而 n 是一个大于 1 小于 8 的数值。为了避免上面描述的问题，使用 n=1 可以避免那些设备的造成的错误。

SCSI 磁带配置

一些 SCSI 磁带设备的启动设置能够使用下面的格式来进行：

st=buf_size[,write_threshold[,max_bufs]]

前面的两个数字指定单元的大小（kB），缺省的值 buf_size 是 32kB，最大的值可以指定为 16384kB。 write_threshold 是磁带得到的缓存区大小，缺省的是 30kB。其最大的缓存值依据不同的驱动设备的个数而得到不同的值，缺省值是两个设备。缺省的格式可能象下面这样

st=32,30,2

你能够在核心源码的 scsi 目录下的 README.st 中看到所有的细节。

Adaptec aha151x, aha152x, aic6260, aic6360, SB16-SCSI 配置

在这一句中 aha 数值代表适配卡类型，aic 数值表示适配卡的 SCSI 芯片类型，也包括象 Soundblaster-16 这样的 SCSI 设备。

SCSI 主设备探测程序将从已经安装好的 BIOS 中进行查找，如果没有的话，该检测将不会找到你的设备。那么，你就必须使用以下格式的启动参数：

aha152x=iobase[,irq[,scsi-id[,reconnect[,parity]]]]

如果驱动程序是以调试模式编译的话，第六个值能够被指定设置调试的级别。

其他的参数已经在上面描述过了。值得一提的是 reconnect 参数如果是非零值就能够允许设备"断连和重新连接"。下面是一个例子。

aha152x=0x340,11,7,1

要注意到的是参数必须按指定的顺序来设定，这意味着如果你需要指定奇偶参数的话你就必须指定其他的所有参数。

Adaptec aha154x 配置

aha1542 系列的适配卡上有一个 i82077 软盘控制器，aha1540 系列的卡没有。这种卡叫做总线主控卡，它们能够通过参数的设置"合理"的与其他设备共享总线。它们的启动参数就象下面这样：

aha1542=iobase[,buson,busoff[,dmaspeed]]

通常可用的 iobase 值会是 0x130，0x134，0x230，0x234，0x330，0x334 其中的一个。兼容的卡能够允许使用其他值。

buson, busoff 值表示的是该卡占用 ISA 总线的时间（以微秒计）。缺省值是 11 微秒开，4 微秒关，这样其他的卡（比如说基于 ISA 总线的 LANCE 以太网卡）就能够有机会访问 ISA 总线。

dmaspeed 值代表直接存储访问 （DMA） 的传输速度 （以MB/秒为单位）。缺省值是 5MB/秒。较新版本的卡允许你使用软件设置来选择该值，老版本的卡使用跳线来设置。如果你的主板支持的话，你能够将该值提高到 10MB/秒。如果使用 5MB/秒以上的传输速度，你就应该进行很小心的实验。

Adaptec aha274x, aha284x, aic7xxx 配置

这些板卡能够接受象下面这样格式的参数：

aic7xxx=extended,no_reset

extended 值，如果是非零的话，表明大容量磁盘的扩展转换模式可以被使用。而 no_reset 值如果是非零的话，告诉驱动程序在设置 SCSI 卡后重新启动时不要重新设置 SCSI 总线。

AdvanSys SCSI Hosts configuration (`advansys=')

AdvanSys 驱动程序能够接收（最多） 4 个 I/O 地址用于来探测 AdvanSys SCSI 卡。要注意的是这些值（如果使用了它们）并不会对 EISA 总线或者 PCI 总线的检测有任何作用。它们只能用来检测 ISA 总线和 VLB 总线型的卡。另外，如果驱动程序是使用调试模式编译的话，调试级别能够通过加入一个 0xdeb[value] 参数来设定。 value 可以是 0-f（16进制），代表可以得到多达 16 个级别的调试信息。

AM53C974

AM53C974=host-scsi-id,target-scsi-id,max-rate,max-offset

BusLogic SCSI Hosts 配置 (`BusLogic=')

BusLogic=N1,N2,N3,N4,N5,S1,S2,...

作为更深层次的讨论，我们来分析一下 BusLogic 命令行参数，参考一下 /usr/src/linux/drivers/scsi/BusLogic.c (在我看的核心版本中是3149-3270行). 下面的文字是一段精辟的摘录

参数 N1-N5 是整数。参数 S1 是字符串。N1 是适配卡的 I/O 地址。 N2 是标记队列深度（Tagged Queue Depth），是为那些支持标记队列（Tagged Queue）的目标设备而设置的。 N3 是总线停滞时间（以秒计），这是表示从 SCSI 适配卡重新启动 SCSI 总线到发出一个 SCSI 指令之间的时间。 N4 是区域选项（只适合特定的单个适配卡） N5 是全局选项（针对所有的适配卡）

字符串参数用来对于标记队列控制（TQ:Default，TQ:Enable，TQ:Disable，TQ:<Per-Target-Spec>），出错处理（ER:Default，ER:HardReset，ER:BusDeviceReset，ER:None，ER:<Per-Target-Spec>）和适配卡检测（NoProbe，NoProbeISA，NoProbePCI）。

EATA/DMA 配置

缺省的需要检测的 I/O 端口能够使用以下的参数来改变：

eata=iobase,iobase,....

Future Domain TMC-16x0 配置

fdomain=iobase,irq[,adapter_id]

Great Valley Products (GVP) SCSI 控制器配置

gvp11=dma_transfer_bitmask

Future Domain TMC-8xx, TMC-950 配置

tmc8xx=mem_base,irq

在这里， mem_base 值是卡所使用的内存映射的 I/O 区域值。常见的值会是 0xc8000，0xca000，0xcc000，0xce000，0xdc000，0xde000。

IN2000 配置

in2000=S

这里 S 是一个用逗号分隔的关键字 [：值] 可以被识别的关键字（有可能伴随着值）是： ioport:addr, noreset, nosync:x, period:ns, disconnect:x,debug:x, proc:x. 如果你要了解这些参数的功能的话，请看 /usr/src/linux/drivers/scsi/in2000.c.

NCR5380 和 NCR53C400 配置

这个启动参数遵循以下的格式

ncr5380=iobase,irq,dma

或者

ncr53c400=iobase,irq

如果卡没有使用中断，那么 IRQ 值 255（0xff）将被用来屏蔽中断。 IRQ 值 254 表示自动检测，更多的细节可以从下面的文档中得到。 /usr/src/linux/drivers/scsi/README.g_NCR5380.

NCR53C8xx 配置

ncr53c8xx=S

这里 S 是一个用逗号分隔的关键字 [：值] 可以被识别的关键字（有可能伴随着值）是： mpar (master_parity), spar (scsi_parity),disc (disconnection), specf (special_features), ultra (ultra_scsi),fsn (force_sync_nego), tags (default_tags), sync (default_sync), verb (verbose), debug (debug), burst (burst_max). 如果需要了解这些值的功能，请参考 /usr/src/linux/drivers/scsi/ncr53c8xx.c.

NCR53c406a 配置

ncr53c406a=iobase[,irq[,fastpio]]

指定 irq = 0 适用于无中断驱动模式。设置 fastpio = 1 设置为快速的处理器 I/O（PIO）模式，0 是慢速的处理器 I/O（PIO）模式。

IOMEGA PPA3 配置

ppa=iobase[,speed_high[,speed_low[,nybble]]]

这里 iobase 的值是并口的地址（缺省值是 0x378）， speed_high 是在数据处理时延迟时间（以微秒为单位，缺省值是 1）， speed_low 是端口其他状态下的延迟时间（以微秒为单位，缺省值是 6）， nybble 是一个 BOOL 值，表示是不是强制使用半个字节（4个位）的工作模式，缺省值是"假"。更多细节请参考 /usr/src/linux/drivers/scsi/README.ppa.

Pro Audio Spectrum 配置

PAS16 适配卡使用 NC5380 SCSI 芯片，较新的版本支持免跳线模式。启动参数是下列格式：

pas16=iobase,irq

不同点是你可以指定 IRQ 的值是 255，这样你就可让驱动程序不要使用中断，当然这样会降低性能。通常 iobase 的值是0x388。

Seagate ST-0x 配置

如果你的卡没有在启动的时候被检测到，你需要使用下面格式的启动参数：

st0x=mem_base,irq

这里 mem_base 值是卡所使用的内存映射的 I/O 区域值。通常的值会是 0xc8000，0xca000，0xcc000，0xce000，0xdc000，0xde000。

Trantor T128 配置

这种卡也是使用 NCR5380 芯片组，并且接受以下的选项：

t128=mem_base,irq

mem_base 的值0xc8000，0xcc000，0xdc000，0xd8000。

UltraStor 14F/34F 配置

检测出的缺省的 I/O 端口列表能够被

eata=iobase,iobase,....

所改变。

WD7000 配置

wd7000=irq,dma,iobase

Commodore Amiga A2091/590 SCSI 控制器配置

wd33c93=S

这里 S 是一个用逗号分隔的字符串选项。可以被识别的选项字是： nosync:bitmask, nodma:x, eriod:ns, disconnect:x, debug:x, clock:x, next．详细说明请参考 /usr/src/linux/drivers/scsi/wd33c93.c.

硬盘驱动器

IDE 硬盘驱动器/光驱驱动程序参数

IDE 驱动程序可以接受的参数有很多，其范围包括从磁盘规格到有缺陷的控制器芯片的支持。指定驱动程序参数的同时需要使用 "hdX=" 的格式来指定驱动器。 X 的范围是从 "a" 到 "h"。

非驱动器选项使用前缀 "hd=" 来指定。注意如果将驱动器选项作用于非驱动器选项也可以工作，而且选项也能够象你所期望的那样被应用。

同时还要注意到的是 "hd=" 格式也能够用于按照规定的顺序（从 a 到 h）检索到下一个没有指定的驱动器。在下面的讨论中，我们可以看到 "hd=" 选项将会被短暂的引用。需要了解更多细节的话，参考 linux/drivers/block 目录下的 README.ide

`hd=cyls,heads,sects[,wpcom[,irq]]' 选项

这些选项用来指定磁盘的物理参数。前面三个参数是必须的。柱面/磁头/磁道三个参数将被 fdisk 程序所使用。如果是 IDE 的硬盘驱动器，"写补偿"值会被忽略掉。指定的 IRQ 值是接口程序所使用的，所以其实并不能被称为真正意义上的指定的驱动器参数。

`hd=serialize' 选项

具有双 IDE 接口的 CMD-640 芯片在设计上是有缺陷的。这个缺陷是当第二个接口与第一个接口被同时使用时，将会破坏你的数据。使用这个选项能够使你的接口永远不会同时使用。

`hd=dtc2278'选项

这个选项告诉驱动程序你拥有一个 DTC-2278D 的 IDE 接口。驱动程序就会试图使用 DTC 的指定操作来激活第二个接口并启动快速传送模式。

`hd=noprobe'选项

不要检测该硬盘驱动器。例如，

hdb=noprobe hdb=1166,7,17

将会屏蔽掉检测，可是仍然指定了驱动器的物理参数，因为这样才能够将驱动器登记成为一个有效的、可用的块设备。

`hd=nowerr'选项

一些驱动器具有 WRERR_STAT 位，并且永久有效。这个选项忽略该位。

`hd=cdrom'选项

这个选项告诉 IDE 驱动程序有一个 ATAPI 兼容的光盘驱动器。在大部分情况下光盘驱动器会被自动的识别，但是对于不能识别的光盘驱动器来说，这个选项是很有用的。

标准的 ST-506 磁盘驱动程序参数 (`hd=')

标准的磁盘驱动程序可以接受磁盘的物理参数，就象上面的 IDE 设备那样。注意无论怎样它都只希望接受三个参数（柱面/磁头/磁道）-- 过多或过少的参数都会被忽略掉。当然，它只接受 "hd=" 这样的参数，象 "had=" 参数这样的在这里是无效的。下面是它的格式：

hd=cyls,heads,sects

如果装有两个磁盘驱动器，上面的工作需要重复的进行以配置第二个磁盘驱动器。

XT 磁盘驱动程序参数 (`xd=')

如果你不幸使用了一些些老掉牙的、8 位的和使用惊人的 125kB/s 传输速度的卡，这些参数会对你有帮助。如果它们不能被识别的话，你只能使用以下格式的启动参数：

xd=type,irq,iobase,dma_chan

type 值指定该卡的制造厂商，下面是厂商的值及对应的名字： 0= 普通卡; 1=DTC; 2,3,4=Western Digital,5,6,7=Seagate; 8=OMTI. 同一厂家出厂的不同类型的卡的区别由 BIOS 字符串来指定，如果指定 type，这些也就没有用了。

函数 xd_setup() 不检查这些值，并且会假设你已经输入了全部的四个值。不要让它失望。这里有一个 WD1002 控制器示范用法--假设 BIOS 被关掉/移走了--使用缺省的 XT 控制参数

xd=2,5,0x320,3

Syquest's EZ*可移动磁盘

ez=iobase[,irq[,rep[,nybble]]]

IBM MCA总线设备

请同时参考 /usr/src/linux/Documentation/mca.txt.

PS/2 ESDI hard disks

有可能按下面的方法在启动时指定你所需要的磁盘物理参数。

ed=cyls,heads,sectors.

对于ThinkPad-720, 要加上下面的选项

tp720=1.

IBM Microchannel SCSI Subsystem 配置

ibmmcascsi=N

这里 N 是子系统的pun (SCSI ID)

CD-ROMs (Non-SCSI/ATAPI/IDE)

Aztech 接口

语法是：

aztcd=iobase[,magic_number]

如果你设置 magic_number 值为0x79，那么该驱动程序尝试在任何一个未知的固件上面执行。其他的值都会被忽略掉。

MicroSolutions `backpack' 光驱接口

语法：

bpcd=iobase

CDU-31A 和 CDU-33A Sony 接口

这种光盘驱动器的接口会出现在一些 Pro Audio Spectrum 声卡及其他支持 Sony 驱动接口的卡上。语法是：

cdu31a=iobase,[irq[,is_pas_card]]

指定一个为 0 的 IRQ 告诉驱动程序该硬件不支持中断（如一些 PAS 卡）。如果你的卡支持中断，就要使用它们，这样可以减少驱动程序的 CPU 占用时间。

对于 is_pas_card 选项来说，如果使用 Pro Audio Spectrum 的卡则应该输入 "PAS"，否则就不需要指定了。

CDU-535 Sony 接口

该光盘驱动器接口的语法如下

sonycd535=iobase[,irq]

如果你要指定 IRQ 值的话，0 可以被当成一个标志位被填到 I/O 地址中。

GoldStar 接口

该光盘驱动器的接口语法是：

gscd=iobase

ISP16 光驱接口

语法：

isp16=[iobase[,irq[,dma[,type]]]]

（三个整数值，一个字符串）。如果 type 的值是 "noisp16" 的话，接口不会被配置。其他可以被接受的 type 值包括： `Sanyo", `Sony', `Panasonic' 和 `Mitsumi'．

Mitsumi标准接口

这种光盘驱动器接口的语法是：

mcd=iobase,[irq[,wait_value]]

这里 wait_value 被用来设置为内部故障的超时时间。能否实现还需要依靠在编译时的定义而定。 Mitsumi FX400 是一种不使用 mcd 驱动程序的 IDE/ATAPI 光盘驱动器。.

Mitsumi XA/MultiSession接口

这是与我们上面介绍的一样的硬件，只不过该驱动程序拥有更多的特性。语法：

mcdx=iobase[,irq]

Optics Storage 接口

语法为：

optcd=iobase

Phillips CM206 接口

语法是：

cm206=[iobase][,irq]

该驱动程序会假定所给的 3 到 11 之间的值是设置的 IRQ 值，数值在 0x300 到 0x370 之间的值是 I/O 端口号，因此你可以指定一个，或者可以指定两个，且没有特殊的位置要求。它也接受 "cm206=auto" 参数来实现自动检测。

The Sanyo 接口

语法是：

sjcd=iobase[,irq[,dma_channel]]

SoundBlaster Pro 接口

语法是：

sbpcd=iobase,type

这里 type 是下面这些字符串的一种（大小写敏感的）： `SoundBlaster', `LaserMate', 或 `SPEA'. I/O 地址是光盘驱动器接口的，并不是声卡的一部分。

以太网络设备

不同的驱动程序使用不同的参数，但是至少它们都会要使用一个 IRQ，一个 I/O 端口地址，一个名字。下面是最为普遍的参数设置格式：

ether=irq,iobase[,param_1[,...param_8]],name

第一个非数值的参数被作为名字使用。 param_n 的值（如果可以使用的话）对于不同的卡/驱动程序来说往往具有不同的含义。典型的 param_n 的值用来指定象共享的内存地址，接口选择，DMA 通道等等。

该参数最普遍的用法是强迫进行第二以太网卡的检测。因为作为缺省的情况来说，内核只是检测第一块以太网卡。下面是实现第二以太网卡检测的简单方法：

ether=0,0,eth1

注意这里 IRQ 和 I/O 的值都是 0，这个表示值需要进行自动检测。

以太网的 HowTo 文件对于多网卡的使用，网卡/驱动程序的指定， param_n 数值的使用都有详细的介绍。有兴趣的读者可以参考该文档中对自己拥有的卡的说明。

软盘驱动器驱动程序

软盘驱动程序选项有很多，它们在 linux/drivers/block 目录下的 README.fd 中列举出来。这些信息就是摘自那个文件。

floppy=mask,allowed_drive_mask

设置允许进行掩码设置的驱动程序将掩码设置为 mask。在缺省情况下，只有每个软盘控制器的 0 号和 1 号单元允许这样做。这样规定的原因是有一些非标准的硬件（华硕的 PCI 主板）在访问 2 号或者 3 号单元时，会令键盘发生问题。该选项差不多已被 cmos 选项所取代了。

floppy=all_drives

为所有的软盘驱动器设置驱动器掩码。如果你在一个软盘控制器上拥有两个驱动器的话，你就可以这么做。

floppy=asus_pci

设置掩码为只允许 0 号和 1 号单元。（缺省值）

floppy=daring

告诉软盘驱动程序你有一个比较好的软盘控制器。这样的设置可以使你的设备运行得更加有效和顺利，但是对于某些特定的控制器，这可能会引起错误，也可能会加快某些操作的速度。

floppy=0,daring

告诉软盘驱动程序你的软盘控制器需要谨慎的运行。

floppy=one_fdc

告诉软盘驱动程序你只有一个软盘控制器。（缺省值）

floppy=two_fdc or floppy=address,two_fdc

告诉软盘驱动程序你拥有两个软盘控制器。第二个控制器假设位于 address 值。如果 address 的值没有给出的话，0x370 被当成假想位置。

floppy=thinkpad

告诉软盘驱动程序你有一个 Thinkpad 电脑。Thinkpad 的磁盘变更线路与通常的机器相反。

floppy=0,thinkpad

告诉软盘驱动程序你没有一个 Thinkpad 电脑。

floppy=drive,type,cmos

设置 CMOS 的类型为 type 值。条件是驱动器在掩码中被置"允许"。如果你有两个以上的软盘驱动器（在实际的 CMOS 设置中只能设置两个），或者你的 BIOS 使用的是非标准的 CMOS 类型，这是非常有用的。把前面两个软盘驱动器的 CMOS 设置为 0（缺省值）使得软盘驱动程序从实际的 CMOS 设置中读取它们的信息。

floppy=unexpected_interrupts

当接收到一个异常时显示相应的消息。（缺省行为）

floppy=no_unexpected_interrupts or floppy=L40SX

如果出现异常，也不要提示。IBM L40SX 在某些特定的显示模式下需要这个选项。（这看起来象是视频和软盘之间有某种交互关系。异常中断只会影响性能，所以能够被安全的忽略）

声卡驱动程序

声卡驱动程序也能够接受启动参数来替代编译时使用的值。这种方法并不值得推荐，因为这样会更复杂。参数说明在 /linux/drivers/sound/Readme.Linux 文件中描叙。它接受如下格式的启动参数：

sound=device1[,device2[,device3...[,device10]]]

这里每个 deviceN 是类似于 0xTaaaId 这样格式的值，其中各字符表示为：

T - 设备类型: 1=FM, 2=SB, 3=PAS, 4=GUS, 5=MPU401, 6=SB16, 7=SB16-MPU401。

aaa - 16 进制的 I/O 地址。

I - 16 进制表示的中断地址 。

d - DMA 通道号。

这样的格式看起来是很混乱的，你最好在编译的时候就使用你知道的值。使用 "sound=0" 的参数将会完全屏蔽声卡驱动程序。

ISDN 驱动程序

ICN ISDN 驱动程序

语法：

icn=iobase,membase,icn_id1,icn_id2

这里 icn_id1 和 icn_id2 是两个字符串，用来为核心消息提供卡的名字。

PCBIT ISDN 驱动程序

语法：

pcbit=membase1,irq1[,membase2,irq2]

这里 membaseN 是第 N 块卡其共享内存的地址，irqN 是第 N 块卡的中断值。缺省值是 IRQ 5 和内存地址 0xD0000。

Teles ISDN 驱动程序

语法：

teles=iobase,irq,membase,protocol,teles_id

这里 iobase 是卡的 I/O 端口地址，membase，irq 的意义与上面的一样， teles_id 是唯一的 ASCII 字符串标识。

串口驱动程序

RISCom/8 多串口驱动程序 (`riscom8=')

语法:

riscom=iobase1[,iobase2[,iobase3[,iobase4]]]

更多的细节请参考 /usr/src/linux/Documentation/riscom8.txt.

DigiBoard 驱动程序 (`digi=')

如果该选项被使用，则应该使用 6 个参数。语法：

digi=status,type,altpin,numports,iobase,membase

参数可以是整数值，也可以是字符串值。如果使用了字符串，则 iobase 和 membase 参数需要使用 16 进制的形式。整型参数值按顺序为： status (允许(1) 或屏蔽(0)该卡), type (PC/Xi(0), PC/Xe(1), PC/Xeve(2), PC/Xem(3)), altpin (允许(1)或屏蔽(0) alternate pin排列), numports (该卡的端口数目), iobase (该卡设置的I/O 端口号 (16进制)), membase (内存窗口的基地址(16进制)). 所以，下面两个不同格式的参数形式其实是一样的：

digi=E,PC/Xi,D,16,200,D0000
digi=1,0,0,16,0x200,851968

更多的细节请参考 /usr/src/linux/Documentation/digiboard.txt.

Baycom 串/并口无线 Modem

语法：

baycom=iobase,irq,modem

只有三个参数；如果有多张卡，就使用多个该命令。 modem 参数是一个字符串，值是 ser12，ser12*，par96，par96* 中的一个。这里 "*" 代表使用软件 DCD。ser12 和 par96 用来选择所支持的 modem 类型。更多的细节请参考 /usr/src/linux/drivers/net/README.baycom.

Soundcard 无线 Modem 驱动程序

语法：

soundmodem=iobase,irq,dma[,dma2[,serio[,pario]]],0,mode

除了最后一个参数以外其他的都是整型值；你可能注意到参数中有一个 0，需要该数值是因为在设置代码中有一个错误。模式参数是一个字符串，其语法是 hw:modem。这里 hw 是"sbc"，"wss"，"wssfdx" 中的一个值，modem 是 "afsk1200"，"fsk9600" 中的一个值。

打印驱动程序

`lp='

对于 1.3.75 版本以后的核心来说，你可以告诉打印驱动程序你使用了或没有使用哪个并行端口。如果你不想让打印驱动程序取得所有可用的并口，后者是非常有用的，这样其他的驱动程序（比如说 PLIP，PPA）就能够使用那些端口。

参数的格式是多个 I/O 地址及 IRQ 对。举例来说， lp=0x3bc,0,0x378,7 将使用位于 0x3bc 地址的端口， "无 IRQ" (轮询 IRQ) 模式，然后使用位于 0x378 地址，IRQ 为 7 的端口。位于地址 0x278 的端口（如果有的话）不会被检测，因为自动检测模式只发生于没有 "lp=" 参数的情况下。如果需要屏蔽打印驱动程序的话，使用 lp=0 就可以实现。

WDT500/501驱动程序

语法：

wdt=io,irq

鼠标驱动程序

`bmouse=irq'

总线型鼠标驱动程序只能接受一个参数，也就是该硬件需要的 IRQ 值。

`msmouse=irq'

对于微软兼容鼠标来说参数与前面总线鼠标是一样的。

ATARI鼠标设置

atamouse=threshold[,y-threshold]

如果只有一个参数，该参数同时代表 x 起点坐标和 y 起点坐标。如果有两个参数，则第一个是 x 起点坐标，第二个是 y 起点坐标。这些值必须是在 1 到 20 之间（包括 20）；缺省值是 2。

视频设备

`no-scroll'

该选项告诉控制台驱动程序不要使用硬件滚动模式（滚动模式在将屏幕图象移动到图形储存器中而不是移动数据时非常有效）。一些 Braille 机器会需要它的。

作者

Linus Torvalds

参考

klogd(8), lilo.conf(5), lilo(8), mount(8), rdev(8).

该手册页的大部分内容来自 Paul Gortmaker 写的 Boot Parameter HowTo（1.0.1）版本。在该 HowTo 中还可以找到更多的有关信息。

#p#

NAME

bootparam - Introduction to boot time parameters of the Linux kernel  

DESCRIPTION

The Linux kernel accepts certain `command line options' or `boot time parameters' at the moment it is started. In general this is used to supply the kernel with information about hardware parameters that the kernel would not be able to determine on its own, or to avoid/override the values that the kernel would otherwise detect.

When the kernel is booted directly by the BIOS (say from a floppy to which you copied a kernel using `cp zImage /dev/fd0'), you have no opportunity to specify any parameters. So, in order to take advantage of this possibility you have to use software that is able to pass parameters, like LILO or loadlin. For a few parameters one can also modify the kernel image itself, using rdev, see rdev(8) for further details.

The LILO program (LInux LOader) written by Werner Almesberger is the most commonly used. It has the ability to boot various kernels, and stores the configuration information in a plain text file. (See lilo(8) and lilo.conf(5).) LILO can boot DOS, OS/2, Linux, FreeBSD, UnixWare, etc., and is quite flexible.

The other commonly used Linux loader is `LoadLin' which is a DOS program that has the capability to launch a Linux kernel from the DOS prompt (with boot-args) assuming that certain resources are available. This is good for people that want to launch Linux from DOS.

It is also very useful if you have certain hardware which relies on the supplied DOS driver to put the hardware into a known state. A common example is `SoundBlaster Compatible' sound cards that require the DOS driver to twiddle a few mystical registers to put the card into a SB compatible mode. Booting DOS with the supplied driver, and then loading Linux from the DOS prompt with loadlin avoids the reset of the card that happens if one rebooted instead.

THE ARGUMENT LIST

The kernel command line is parsed into a list of strings (boot arguments) separated by spaces. Most of the boot args take the form of:

name[=value_1][,value_2]...[,value_10]

where `name' is a unique keyword that is used to identify what part of the kernel the associated values (if any) are to be given to. Note the limit of 10 is real, as the present code only handles 10 comma separated parameters per keyword. (However, you can re-use the same keyword with up to an additional 10 parameters in unusually complicated situations, assuming the setup function supports it.)

Most of the sorting goes on in linux/init/main.c. First, the kernel checks to see if the argument is any of the special arguments `root=', `nfsroot=', `nfsaddrs=', `ro', `rw', `debug' or `init'. The meaning of these special arguments is described below.

Then it walks a list of setup functions (contained in the bootsetups array) to see if the specified argument string (such as `foo') has been associated with a setup function (`foo_setup()') for a particular device or part of the kernel. If you passed the kernel the line foo=3,4,5,6 then the kernel would search the bootsetups array to see if `foo' was registered. If it was, then it would call the setup function associated with `foo' (foo_setup()) and hand it the arguments 3, 4, 5 and 6 as given on the kernel command line.

Anything of the form `foo=bar' that is not accepted as a setup function as described above is then interpreted as an environment variable to be set. A (useless?) example would be to use `TERM=vt100' as a boot argument.

Any remaining arguments that were not picked up by the kernel and were not interpreted as environment variables are then passed onto process one, which is usually the init program. The most common argument that is passed to the init process is the word `single' which instructs init to boot the computer in single user mode, and not launch all the usual daemons. Check the manual page for the version of init installed on your system to see what arguments it accepts.

GENERAL NON-DEVICE SPECIFIC BOOT ARGS

`init=...'

This sets the initial command to be executed by the kernel. If this is not set, or cannot be found, the kernel will try /etc/init, then /bin/init, then /sbin/init, then /bin/sh and panic if all of this fails.

`nfsaddrs=...'

This sets the nfs boot address to the given string. This boot address is used in case of a net boot.

`nfsroot=...'

This sets the nfs root name to the given string. If this string does not begin with '/' or ',' or a digit, then it is prefixed by `/tftpboot/'. This root name is used in case of a net boot.

`no387'

(Only when CONFIG_BUGi386 is defined.) Some i387 coprocessor chips have bugs that show up when used in 32 bit protected mode. For example, some of the early ULSI-387 chips would cause solid lockups while performing floating point calculations. Using the `no387' boot arg causes Linux to ignore the maths coprocessor even if you have one. Of course you must then have your kernel compiled with math emulation support!

`no-hlt'

(Only when CONFIG_BUGi386 is defined.) Some of the early i486DX-100 chips have a problem with the `hlt' instruction, in that they can't reliably return to operating mode after this instruction is used. Using the `no-hlt' instruction tells Linux to just run an infinite loop when there is nothing else to do, and to not halt the CPU. This allows people with these broken chips to use Linux.

`root=...'

This argument tells the kernel what device is to be used as the root filesystem while booting. The default of this setting is determined at compile time, and usually is the value of the root device of the system that the kernel was built on. To override this value, and select the second floppy drive as the root device, one would use `root=/dev/fd1'. (The root device can also be set using rdev(8).)

The root device can be specified symbolically or numerically. A symbolic specification has the form /dev/XXYN, where XX designates the device type (`hd' for ST-506 compatible hard disk, with Y in `a'-`d'; `sd' for SCSI compatible disk, with Y in `a'-`e'; `ad' for Atari ACSI disk, with Y in `a'-`e', `ez' for a Syquest EZ135 parallel port removable drive, with Y=`a', `xd' for XT compatible disk, with Y either `a' or `b'; `fd' for floppy disk, with Y the floppy drive number - fd0 would be the DOS `A:' drive, and fd1 would be `B:'), Y the driver letter or number, and N the number (in decimal) of the partition on this device (absent in the case of floppies). Recent kernels allow many other types, mostly for CD-ROMs: nfs, ram, scd, mcd, cdu535, aztcd, cm206cd, gscd, sbpcd, sonycd, bpcd. (The type nfs specifies a net boot; ram refers to a ram disk.)

Note that this has nothing to do with the designation of these devices on your file system. The `/dev/' part is purely conventional.

The more awkward and less portable numeric specification of the above possible root devices in major/minor format is also accepted. (E.g., /dev/sda3 is major 8, minor 3, so you could use `root=0x803' as an alternative.)

`ro' and `rw'

The `ro' option tells the kernel to mount the root filesystem as `readonly' so that filesystem consistency check programs (fsck) can do their work on a quiescent file system. No processes can write to files on the filesystem in question until it is `remounted' as read/write capable, e.g., by `mount -w -n -o remount /'. (See also mount(8).)

The `rw' option tells the kernel to mount the root filesystem read/write. This is the default.

The choice between read-only and read/write can also be set using rdev(8).

`reserve=...'

This is used to protect I/O port regions from probes. The form of the command is:

reserve=iobase,extent[,iobase,extent]...

In some machines it may be necessary to prevent device drivers from checking for devices (auto-probing) in a specific region. This may be because of hardware that reacts badly to the probing, or hardware that would be mistakenly identified, or merely hardware you don't want the kernel to initialize.

The reserve boot-time argument specifies an I/O port region that shouldn't be probed. A device driver will not probe a reserved region, unless another boot argument explicitly specifies that it do so.

For example, the boot line

reserve=0x300,32 blah=0x300

keeps all device drivers except the driver for `blah' from probing 0x300-0x31f.

`mem=...'

The BIOS call defined in the PC specification that returns the amount of installed memory was only designed to be able to report up to 64MB. Linux uses this BIOS call at boot to determine how much memory is installed. If you have more than 64MB of RAM installed, you can use this boot arg to tell Linux how much memory you have. The value is in decimal or hexadecimal (prefix 0x), and the suffixes `k' (times 1024) or `M' (times 1048576) can be used. Here is a quote from Linus on usage of the `mem=' parameter.

``The kernel will accept any `mem=xx' parameter you give it, and if it turns out that you lied to it, it will crash horribly sooner or later. The parameter indicates the highest addressable RAM address, so `mem=0x1000000' means you have 16MB of memory, for example. For a 96MB machine this would be `mem=0x6000000'.

NOTE NOTE NOTE: some machines might use the top of memory for BIOS cacheing or whatever, so you might not actually have up to the full 96MB addressable. The reverse is also true: some chipsets will map the physical memory that is covered by the BIOS area into the area just past the top of memory, so the top-of-mem might actually be 96MB + 384kB for example. If you tell linux that it has more memory than it actually does have, bad things will happen: maybe not at once, but surely eventually.''

You can also use the boot argument `mem=nopentium' to turn off 4 MB pagetables on kernels configured for IA32 systems with a pentium or newer CPU.

`panic=N'

By default the kernel will not reboot after a panic, but this option will cause a kernel reboot after N seconds (if N > 0). This panic timeout can also be set by "echo N > /proc/sys/kernel/panic".

`reboot=[warm|cold][,[bios|hard]]'

(Only when CONFIG_BUGi386 is defined.) Since 2.0.22 a reboot is by default a cold reboot. One asks for the old default with `reboot=warm'. (A cold reboot may be required to reset certain hardware, but might destroy not yet written data in a disk cache. A warm reboot may be faster.) By default a reboot is hard, by asking the keyboard controller to pulse the reset line low, but there is at least one type of motherboard where that doesn't work. The option `reboot=bios' will instead jump through the BIOS.

`nosmp' and `maxcpus=N'

(Only when __SMP__ is defined.) A command-line option of `nosmp' or `maxcpus=0' will disable SMP activation entirely; an option `maxcpus=N' limits the maximum number of CPUs activated in SMP mode to N.

BOOT ARGUMENTS FOR USE BY KERNEL DEVELOPERS

`debug'

Kernel messages are handed off to the kernel log daemon klogd so that they may be logged to disk. Messages with a priority above console_loglevel are also printed on the console. (For these levels, see <linux/kernel.h>.) By default this variable is set to log anything more important than debug messages. This boot argument will cause the kernel to also print the messages of DEBUG priority. The console loglevel can also be set at run time via an option to klogd. See klogd(8).

`profile=N'

It is possible to enable a kernel profiling function, if one wishes to find out where the kernel is spending its CPU cycles. Profiling is enabled by setting the variable prof_shift to a nonzero value. This is done either by specifying CONFIG_PROFILE at compile time, or by giving the `profile=' option. Now the value that prof_shift gets will be N, when given, or CONFIG_PROFILE_SHIFT, when that is given, or 2, the default. The significance of this variable is that it gives the granularity of the profiling: each clock tick, if the system was executing kernel code, a counter is incremented:

profile[address >> prof_shift]++;

The raw profiling information can be read from /proc/profile. Probably you'll want to use a tool such as readprofile.c to digest it. Writing to /proc/profile will clear the counters.

`swap=N1,N2,N3,N4,N5,N6,N7,N8'

Set the eight parameters max_page_age, page_advance, page_decline, page_initial_age, age_cluster_fract, age_cluster_min, pageout_weight, bufferout_weight that control the kernel swap algorithm. For kernel tuners only.

`buff=N1,N2,N3,N4,N5,N6'

Set the six parameters max_buff_age, buff_advance, buff_decline, buff_initial_age, bufferout_weight, buffermem_grace that control kernel buffer memory management. For kernel tuners only.

BOOT ARGUMENTS FOR RAMDISK USE

(Only if the kernel was compiled with CONFIG_BLK_DEV_RAM.) In general it is a bad idea to use a ramdisk under Linux - the system will use available memory more efficiently itself. But while booting (or while constructing boot floppies) it is often useful to load the floppy contents into a ramdisk. One might also have a system in which first some modules (for filesystem or hardware) must be loaded before the main disk can be accessed.

In Linux 1.3.48, ramdisk handling was changed drastically. Earlier, the memory was allocated statically, and there was a `ramdisk=N' parameter to tell its size. (This could also be set in the kernel image at compile time, or by use of rdev(8).) These days ram disks use the buffer cache, and grow dynamically. For a lot of information (e.g., how to use rdev(8) in conjunction with the new ramdisk setup), see /usr/src/linux/Documentation/ramdisk.txt.

There are four parameters, two boolean and two integral.

`load_ramdisk=N'

If N=1, do load a ramdisk. If N=0, do not load a ramdisk. (This is the default.)

`prompt_ramdisk=N'

If N=1, do prompt for insertion of the floppy. (This is the default.) If N=0, do not prompt. (Thus, this parameter is never needed.)

`ramdisk_size=N' or (obsolete) `ramdisk=N'

Set the maximal size of the ramdisk(s) to N kB. The default is 4096 (4 MB).

`ramdisk_start=N'

Sets the starting block number (the offset on the floppy where the ramdisk starts) to N. This is needed in case the ramdisk follows a kernel image.

`noinitrd'

(Only if the kernel was compiled with CONFIG_BLK_DEV_RAM and CONFIG_BLK_DEV_INITRD.) These days it is possible to compile the kernel to use initrd. When this feature is enabled, the boot process will load the kernel and an initial ramdisk; then the kernel converts initrd into a "normal" ramdisk, which is mounted read-write as root device; then /linuxrc is executed; afterwards the "real" root file system is mounted, and the initrd filesystem is moved over to /initrd; finally the usual boot sequence (e.g. invocation of /sbin/init) is performed.

For a detailed description of the initrd feature, see /usr/src/linux/Documentation/initrd.txt.

The `noinitrd' option tells the kernel that although it was compiled for operation with initrd, it should not go through the above steps, but leave the initrd data under /dev/initrd. (This device can be used only once - the data is freed as soon as the last process that used it has closed /dev/initrd.)

BOOT ARGUMENTS FOR SCSI DEVICES

General notation for this section:

iobase -- the first I/O port that the SCSI host occupies. These are specified in hexidecimal notation, and usually lie in the range from 0x200 to 0x3ff.

irq -- the hardware interrupt that the card is configured to use. Valid values will be dependent on the card in question, but will usually be 5, 7, 9, 10, 11, 12, and 15. The other values are usually used for common peripherals like IDE hard disks, floppies, serial ports, etc.

scsi-id -- the ID that the host adapter uses to identify itself on the SCSI bus. Only some host adapters allow you to change this value, as most have it permanently specified internally. The usual default value is 7, but the Seagate and Future Domain TMC-950 boards use 6.

parity -- whether the SCSI host adapter expects the attached devices to supply a parity value with all information exchanges. Specifying a one indicates parity checking is enabled, and a zero disables parity checking. Again, not all adapters will support selection of parity behaviour as a boot argument.

`max_scsi_luns=...'

A SCSI device can have a number of `sub-devices' contained within itself. The most common example is one of the new SCSI CD-ROMs that handle more than one disk at a time. Each CD is addressed as a `Logical Unit Number' (LUN) of that particular device. But most devices, such as hard disks, tape drives and such are only one device, and will be assigned to LUN zero.

Some poorly designed SCSI devices cannot handle being probed for LUNs not equal to zero. Therefore, if the compile time flag CONFIG_SCSI_MULTI_LUN is not set, newer kernels will by default only probe LUN zero.

To specify the number of probed LUNs at boot, one enters `max_scsi_luns=n' as a boot arg, where n is a number between one and eight. To avoid problems as described above, one would use n=1 to avoid upsetting such broken devices.

SCSI tape configuration

Some boot time configuration of the SCSI tape driver can be achieved by using the following:

st=buf_size[,write_threshold[,max_bufs]]

The first two numbers are specified in units of kB. The default buf_size is 32kB, and the maximum size that can be specified is a ridiculous 16384kB. The write_threshold is the value at which the buffer is committed to tape, with a default value of 30kB. The maximum number of buffers varies with the number of drives detected, and has a default of two. An example usage would be:

st=32,30,2

Full details can be found in the README.st file that is in the scsi directory of the kernel source tree.

Adaptec aha151x, aha152x, aic6260, aic6360, SB16-SCSI configuration

The aha numbers refer to cards and the aic numbers refer to the actual SCSI chip on these type of cards, including the Soundblaster-16 SCSI.

The probe code for these SCSI hosts looks for an installed BIOS, and if none is present, the probe will not find your card. Then you will have to use a boot arg of the form:

aha152x=iobase[,irq[,scsi-id[,reconnect[,parity]]]]

If the driver was compiled with debugging enabled, a sixth value can be specified to set the debug level.

All the parameters are as described at the top of this section, and the reconnect value will allow device disconnect/reconnect if a non-zero value is used. An example usage is as follows:

aha152x=0x340,11,7,1

Note that the parameters must be specified in order, meaning that if you want to specify a parity setting, then you will have to specify an iobase, irq, scsi-id and reconnect value as well.

Adaptec aha154x configuration

The aha1542 series cards have an i82077 floppy controller onboard, while the aha1540 series cards do not. These are busmastering cards, and have parameters to set the ``fairness'' that is used to share the bus with other devices. The boot arg looks like the following.

aha1542=iobase[,buson,busoff[,dmaspeed]]

Valid iobase values are usually one of: 0x130, 0x134, 0x230, 0x234, 0x330, 0x334. Clone cards may permit other values.

The buson, busoff values refer to the number of microseconds that the card dominates the ISA bus. The defaults are 11us on, and 4us off, so that other cards (such as an ISA LANCE Ethernet card) have a chance to get access to the ISA bus.

The dmaspeed value refers to the rate (in MB/s) at which the DMA (Direct Memory Access) transfers proceed. The default is 5MB/s. Newer revision cards allow you to select this value as part of the soft-configuration, older cards use jumpers. You can use values up to 10MB/s assuming that your motherboard is capable of handling it. Experiment with caution if using values over 5MB/s.

Adaptec aha274x, aha284x, aic7xxx configuration

These boards can accept an argument of the form:

aic7xxx=extended,no_reset

The extended value, if non-zero, indicates that extended translation for large disks is enabled. The no_reset value, if non-zero, tells the driver not to reset the SCSI bus when setting up the host adaptor at boot.

AdvanSys SCSI Hosts configuration (`advansys=')

The AdvanSys driver can accept up to four i/o addresses that will be probed for an AdvanSys SCSI card. Note that these values (if used) do not effect EISA or PCI probing in any way. They are only used for probing ISA and VLB cards. In addition, if the driver has been compiled with debugging enabled, the level of debugging output can be set by adding an 0xdeb[0-f] parameter. The 0-f allows setting the level of the debugging messages to any of 16 levels of verbosity.

AM53C974

AM53C974=host-scsi-id,target-scsi-id,max-rate,max-offset

BusLogic SCSI Hosts configuration (`BusLogic=')

BusLogic=N1,N2,N3,N4,N5,S1,S2,...

For an extensive discussion of the BusLogic command line parameters, see /usr/src/linux/drivers/scsi/BusLogic.c (lines 3149-3270 in the kernel version I am looking at). The text below is a very much abbreviated extract.

The parameters N1-N5 are integers. The parameters S1,... are strings. N1 is the I/O Address at which the Host Adapter is located. N2 is the Tagged Queue Depth to use for Target Devices that support Tagged Queuing. N3 is the Bus Settle Time in seconds. This is the amount of time to wait between a Host Adapter Hard Reset which initiates a SCSI Bus Reset and issuing any SCSI Commands. N4 is the Local Options (for one Host Adapter). N5 is the Global Options (for all Host Adapters).

The string options are used to provide control over Tagged Queuing (TQ:Default, TQ:Enable, TQ:Disable, TQ:<Per-Target-Spec>), over Error Recovery (ER:Default, ER:HardReset, ER:BusDeviceReset, ER:None, ER:<Per-Target-Spec>), and over Host Adapter Probing (NoProbe, NoProbeISA, NoSortPCI).

EATA/DMA configuration

The default list of i/o ports to be probed can be changed by

eata=iobase,iobase,....

Future Domain TMC-16x0 configuration

fdomain=iobase,irq[,adapter_id]

Great Valley Products (GVP) SCSI controller configuration

gvp11=dma_transfer_bitmask

Future Domain TMC-8xx, TMC-950 configuration

tmc8xx=mem_base,irq

The mem_base value is the value of the memory mapped I/O region that the card uses. This will usually be one of the following values: 0xc8000, 0xca000, 0xcc000, 0xce000, 0xdc000, 0xde000.

IN2000 configuration

in2000=S

where S is a comma-separated string of items keyword[:value]. Recognized keywords (possibly with value) are: ioport:addr, noreset, nosync:x, period:ns, disconnect:x, debug:x, proc:x. For the function of these parameters, see /usr/src/linux/drivers/scsi/in2000.c.

NCR5380 and NCR53C400 configuration

The boot arg is of the form

ncr5380=iobase,irq,dma

or

ncr53c400=iobase,irq

If the card doesn't use interrupts, then an IRQ value of 255 (0xff) will disable interrupts. An IRQ value of 254 means to autoprobe. More details can be found in the file /usr/src/linux/drivers/scsi/README.g_NCR5380.

NCR53C8xx configuration

ncr53c8xx=S

where S is a comma-separated string of items keyword:value. Recognized keywords are: mpar (master_parity), spar (scsi_parity), disc (disconnection), specf (special_features), ultra (ultra_scsi), fsn (force_sync_nego), tags (default_tags), sync (default_sync), verb (verbose), debug (debug), burst (burst_max). For the function of the assigned values, see /usr/src/linux/drivers/scsi/ncr53c8xx.c.

NCR53c406a configuration

ncr53c406a=iobase[,irq[,fastpio]]

Specify irq = 0 for non-interrupt driven mode. Set fastpio = 1 for fast pio mode, 0 for slow mode.

Pro Audio Spectrum configuration

The PAS16 uses a NC5380 SCSI chip, and newer models support jumperless configuration. The boot arg is of the form:

pas16=iobase,irq

The only difference is that you can specify an IRQ value of 255, which will tell the driver to work without using interrupts, albeit at a performance loss. The iobase is usually 0x388.

Seagate ST-0x configuration

If your card is not detected at boot time, you will then have to use a boot arg of the form:

st0x=mem_base,irq

The mem_base value is the value of the memory mapped I/O region that the card uses. This will usually be one of the following values: 0xc8000, 0xca000, 0xcc000, 0xce000, 0xdc000, 0xde000.

Trantor T128 configuration

These cards are also based on the NCR5380 chip, and accept the following options:

t128=mem_base,irq

The valid values for mem_base are as follows: 0xcc000, 0xc8000, 0xdc000, 0xd8000.

UltraStor 14F/34F configuration

The default list of i/o ports to be probed can be changed by

eata=iobase,iobase,....

WD7000 configuration

wd7000=irq,dma,iobase

Commodore Amiga A2091/590 SCSI controller configuration

wd33c93=S

where S is a comma-separated string of options. Recognized options are nosync:bitmask, nodma:x, period:ns, disconnect:x, debug:x, clock:x, next. For details, see /usr/src/linux/drivers/scsi/wd33c93.c.

HARD DISKS

IDE Disk/CD-ROM Driver Parameters

The IDE driver accepts a number of parameters, which range from disk geometry specifications, to support for broken controller chips. Drive specific options are specified by using `hdX=' with X in `a'-`h'.

Non-drive specific options are specified with the prefix `hd='. Note that using a drive specific prefix for a non-drive specific option will still work, and the option will just be applied as expected.

Also note that `hd=' can be used to refer to the next unspecified drive in the (a, ..., h) sequence. For the following discussions, the `hd=' option will be cited for brevity. See the file README.ide in linux/drivers/block for more details.

The `hd=cyls,heads,sects[,wpcom[,irq]]' options

These options are used to specify the physical geometry of the disk. Only the first three values are required. The cylinder/head/sectors values will be those used by fdisk. The write precompensation value is ignored for IDE disks. The IRQ value specified will be the IRQ used for the interface that the drive resides on, and is not really a drive specific parameter.

The `hd=serialize' option

The dual IDE interface CMD-640 chip is broken as designed such that when drives on the secondary interface are used at the same time as drives on the primary interface, it will corrupt your data. Using this option tells the driver to make sure that both interfaces are never used at the same time.

The `hd=dtc2278' option

This option tells the driver that you have a DTC-2278D IDE interface. The driver then tries to do DTC specific operations to enable the second interface and to enable faster transfer modes.

The `hd=noprobe' option

Do not probe for this drive. For example,

hdb=noprobe hdb=1166,7,17

would disable the probe, but still specify the drive geometry so that it would be registered as a valid block device, and hence usable.

The `hd=nowerr' option

Some drives apparently have the WRERR_STAT bit stuck on permanently. This enables a work-around for these broken devices.

The `hd=cdrom' option

This tells the IDE driver that there is an ATAPI compatible CD-ROM attached in place of a normal IDE hard disk. In most cases the CD-ROM is identified automatically, but if it isn't then this may help.

Standard ST-506 Disk Driver Options (`hd=')

The standard disk driver can accept geometry arguments for the disks similar to the IDE driver. Note however that it only expects three values (C/H/S) -- any more or any less and it will silently ignore you. Also, it only accepts `hd=' as an argument, i.e. `hda=' and so on are not valid here. The format is as follows:

hd=cyls,heads,sects

If there are two disks installed, the above is repeated with the geometry parameters of the second disk.

XT Disk Driver Options (`xd=')

If you are unfortunate enough to be using one of these old 8 bit cards that move data at a whopping 125kB/s then here is the scoop. If the card is not recognised, you will have to use a boot arg of the form:

xd=type,irq,iobase,dma_chan

The type value specifies the particular manufacturer of the card, overriding autodetection. For the types to use, consult the drivers/block/xd.c source file of the kernel you are using. The type is an index in the list xd_sigs and in the course of time types have been added to or deleted from the middle of the list, changing all type numbers. Today (Linux 2.5.0) the types are 0=generic; 1=DTC 5150cx; 2,3=DTC 5150x; 4,5=Western Digital; 6,7,8=Seagate; 9=Omti; 10=XEBEC, and where here several types are given with the same designation, they are equivalent.

The xd_setup() function does no checking on the values, and assumes that you entered all four values. Don't disappoint it. Here is an example usage for a WD1002 controller with the BIOS disabled/removed, using the `default' XT controller parameters:

xd=2,5,0x320,3

Syquest's EZ* removable disks

ez=iobase[,irq[,rep[,nybble]]]

IBM MCA BUS DEVICES

See also /usr/src/linux/Documentation/mca.txt.

PS/2 ESDI hard disks

It is possible to specify the desired geometry at boot time:

ed=cyls,heads,sectors.

For a ThinkPad-720, add the option

tp720=1.

IBM Microchannel SCSI Subsystem configuration

ibmmcascsi=N

where N is the pun (SCSI ID) of the subsystem.

CD-ROMs (Non-SCSI/ATAPI/IDE)

The Aztech Interface

The syntax for this type of card is:

aztcd=iobase[,magic_number]

If you set the magic_number to 0x79 then the driver will try and run anyway in the event of an unknown firmware version. All other values are ignored.

Parallel port CD-ROM drives

Syntax:

pcd.driveN=prt,pro,uni,mod,slv,dly
pcd.nice=nice

where `port' is the base address, `pro' is the protocol number, `uni' is the unit selector (for chained devices), `mod' is the mode (or -1 to choose the best automatically), `slv' is 1 if it should be a slave, and `dly' is a small integer for slowing down port accesses. The `nice' parameter controls the driver's use of idle CPU time, at the expense of some speed.

The CDU-31A and CDU-33A Sony Interface

This CD-ROM interface is found on some of the Pro Audio Spectrum sound cards, and other Sony supplied interface cards. The syntax is as follows:

cdu31a=iobase,[irq[,is_pas_card]]

Specifying an IRQ value of zero tells the driver that hardware interrupts aren't supported (as on some PAS cards). If your card supports interrupts, you should use them as it cuts down on the CPU usage of the driver.

The is_pas_card should be entered as `PAS' if using a Pro Audio Spectrum card, and otherwise it should not be specified at all.

The CDU-535 Sony Interface

The syntax for this CD-ROM interface is:

sonycd535=iobase[,irq]

A zero can be used for the I/O base as a `placeholder' if one wishes to specify an IRQ value.

The GoldStar Interface

The syntax for this CD-ROM interface is:

gscd=iobase

The ISP16 CD-ROM Interface

Syntax:

isp16=[iobase[,irq[,dma[,type]]]]

(three integers and a string). If the type is given as `noisp16', the interface will not be configured. Other recognized types are: `Sanyo", `Sony', `Panasonic' and `Mitsumi'.

The Mitsumi Standard Interface

The syntax for this CD-ROM interface is:

mcd=iobase,[irq[,wait_value]]

The wait_value is used as an internal timeout value for people who are having problems with their drive, and may or may not be implemented depending on a compile time #define. The Mitsumi FX400 is an IDE/ATAPI CD-ROM player and does not use the mcd driver.

The Mitsumi XA/MultiSession Interface

This is for the same hardware as above, but the driver has extended features. Syntax:

mcdx=iobase[,irq]

The Optics Storage Interface

The syntax for this type of card is:

optcd=iobase

The Phillips CM206 Interface

The syntax for this type of card is:

cm206=[iobase][,irq]

The driver assumes numbers between 3 and 11 are IRQ values, and numbers between 0x300 and 0x370 are I/O ports, so you can specify one, or both numbers, in any order. It also accepts `cm206=auto' to enable autoprobing.

The Sanyo Interface

The syntax for this type of card is:

sjcd=iobase[,irq[,dma_channel]]

The SoundBlaster Pro Interface

The syntax for this type of card is:

sbpcd=iobase,type

where type is one of the following (case sensitive) strings: `SoundBlaster', `LaserMate', or `SPEA'. The I/O base is that of the CD-ROM interface, and not that of the sound portion of the card.

ETHERNET DEVICES

Different drivers make use of different parameters, but they all at least share having an IRQ, an I/O port base value, and a name. In its most generic form, it looks something like this:

ether=irq,iobase[,param_1[,...param_8]],name

The first non-numeric argument is taken as the name. The param_n values (if applicable) usually have different meanings for each different card/driver. Typical param_n values are used to specify things like shared memory address, interface selection, DMA channel and the like.

The most common use of this parameter is to force probing for a second ethercard, as the default is to only probe for one. This can be accomplished with a simple:

ether=0,0,eth1

Note that the values of zero for the IRQ and I/O base in the above example tell the driver(s) to autoprobe.

The Ethernet-HowTo has extensive documentation on using multiple cards and on the card/driver specific implementation of the param_n values where used. Interested readers should refer to the section in that document on their particular card.

THE FLOPPY DISK DRIVER

There are many floppy driver options, and they are all listed in README.fd in linux/drivers/block. This information is taken directly from that file.

floppy=mask,allowed_drive_mask

Sets the bitmask of allowed drives to mask. By default, only units 0 and 1 of each floppy controller are allowed. This is done because certain non-standard hardware (ASUS PCI motherboards) mess up the keyboard when accessing units 2 or 3. This option is somewhat obsoleted by the cmos option.

floppy=all_drives

Sets the bitmask of allowed drives to all drives. Use this if you have more than two drives connected to a floppy controller.

floppy=asus_pci

Sets the bitmask to allow only units 0 and 1. (The default)

floppy=daring

Tells the floppy driver that you have a well behaved floppy controller. This allows more efficient and smoother operation, but may fail on certain controllers. This may speed up certain operations.

floppy=0,daring

Tells the floppy driver that your floppy controller should be used with caution.

floppy=one_fdc

Tells the floppy driver that you have only floppy controller (default)

floppy=two_fdc or floppy=address,two_fdc

Tells the floppy driver that you have two floppy controllers. The second floppy controller is assumed to be at address. If address is not given, 0x370 is assumed.

floppy=thinkpad

Tells the floppy driver that you have a Thinkpad. Thinkpads use an inverted convention for the disk change line.

floppy=0,thinkpad

Tells the floppy driver that you don't have a Thinkpad.

floppy=drive,type,cmos

Sets the cmos type of drive to type. Additionally, this drive is allowed in the bitmask. This is useful if you have more than two floppy drives (only two can be described in the physical cmos), or if your BIOS uses non-standard CMOS types. Setting the CMOS to 0 for the first two drives (default) makes the floppy driver read the physical cmos for those drives.

floppy=unexpected_interrupts

Print a warning message when an unexpected interrupt is received (default behaviour)

floppy=no_unexpected_interrupts or floppy=L40SX

Don't print a message when an unexpected interrupt is received. This is needed on IBM L40SX laptops in certain video modes. (There seems to be an interaction between video and floppy. The unexpected interrupts only affect performance, and can safely be ignored.)

THE SOUND DRIVER

The sound driver can also accept boot args to override the compiled in values. This is not recommended, as it is rather complex. It is described in the Readme.Linux file, in linux/drivers/sound. It accepts a boot arg of the form:

sound=device1[,device2[,device3...[,device10]]]

where each deviceN value is of the following format 0xTaaaId and the bytes are used as follows:

T - device type: 1=FM, 2=SB, 3=PAS, 4=GUS, 5=MPU401, 6=SB16, 7=SB16-MPU401

aaa - I/O address in hex.

I - interrupt line in hex (i.e 10=a, 11=b, ...)

d - DMA channel.

As you can see it gets pretty messy, and you are better off to compile in your own personal values as recommended. Using a boot arg of `sound=0' will disable the sound driver entirely.

ISDN DRIVERS

The ICN ISDN driver

Syntax:

icn=iobase,membase,icn_id1,icn_id2

where icn_id1,icn_id2 are two strings used to identify the card in kernel messages.

The PCBIT ISDN driver

Syntax:

pcbit=membase1,irq1[,membase2,irq2]

where membaseN is the shared memory base of the N'th card, and irqN is the interrupt setting of the N'th card. The default is IRQ 5 and membase 0xD0000.

The Teles ISDN driver

Syntax:

teles=iobase,irq,membase,protocol,teles_id

where iobase is the i/o port address of the card, membase is the shared memory base address of the card, irq is the interrupt channel the card uses, and teles_id is the unique ASCII string identifier.

SERIAL PORT DRIVERS

The RISCom/8 Multiport Serial Driver (`riscom8=')

Syntax:

riscom=iobase1[,iobase2[,iobase3[,iobase4]]]

More details can be found in /usr/src/linux/Documentation/riscom8.txt.

The DigiBoard Driver (`digi=')

If this option is used, it should have precisely six parameters. Syntax:

digi=status,type,altpin,numports,iobase,membase

The parameters maybe given as integers, or as strings. If strings are used, then iobase and membase should be given in hexadecimal. The integer arguments (fewer may be given) are in order: status (Enable(1) or Disable(0) this card), type (PC/Xi(0), PC/Xe(1), PC/Xeve(2), PC/Xem(3)), altpin (Enable(1) or Disable(0) alternate pin arrangement), numports (number of ports on this card), iobase (I/O Port where card is configured (in HEX)), membase (base of memory window (in HEX)). Thus, the following two boot prompt arguments are equivalent:

digi=E,PC/Xi,D,16,200,D0000
digi=1,0,0,16,0x200,851968

More details can be found in /usr/src/linux/Documentation/digiboard.txt.

The Baycom Serial/Parallel Radio Modem

Syntax:

baycom=iobase,irq,modem

There are precisely 3 parameters; for several cards, give several `baycom=' commands. The modem parameter is a string that can take one of the values ser12, ser12*, par96, par96*. Here the * denotes that software DCD is to be used, and ser12/par96 chooses between the supported modem types. For more details, see /usr/src/linux/drivers/net/README.baycom.

Soundcard radio modem driver

Syntax:

soundmodem=iobase,irq,dma[,dma2[,serio[,pario]]],0,mode

All parameters except the last are integers; the dummy 0 is required because of a bug in the setup code. The mode parameter is a string with syntax hw:modem, where hw is one of sbc, wss, wssfdx and modem is one of afsk1200, fsk9600.

THE LINE PRINTER DRIVER

`lp='

Syntax:

lp=0
lp=auto
lp=reset
lp=port[,port...]

You can tell the printer driver what ports to use and what ports not to use. The latter comes in handy if you don't want the printer driver to claim all available parallel ports, so that other drivers (e.g. PLIP, PPA) can use them instead.

The format of the argument is multiple port names. For example, lp=none,parport0 would use the first parallel port for lp1, and disable lp0. To disable the printer driver entirely, one can use lp=0.

WDT500/501 driver

Syntax:

wdt=io,irq

MOUSE DRIVERS

`bmouse=irq'

The busmouse driver only accepts one parameter, that being the hardware IRQ value to be used.

`msmouse=irq'

And precisely the same is true for the msmouse driver.

ATARI mouse setup

atamouse=threshold[,y-threshold]

If only one argument is given, it is used for both x-threshold and y-threshold. Otherwise, the first argument is the x-threshold, and the second the y-threshold. These values must lie between 1 and 20 (inclusive); the default is 2.

VIDEO HARDWARE

`no-scroll'

This option tells the console driver not to use hardware scroll (where a scroll is effected by moving the screen origin in video memory, instead of moving the data). It is required by certain Braille machines.

AUTHORS

Linus Torvalds (and many others)

SEE ALSO

klogd(8), lilo.conf(5), lilo(8), mount(8), rdev(8)

Large parts of this man page have been derived from the Boot Parameter HOWTO (version 1.0.1) written by Paul Gortmaker. More information may be found in this (or a more recent) HOWTO. An uptodate source of information is /usr/src/linux/Documentation/kernel-parameters.txt.