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1 | .\" Copyright (c) 1995,1997 Paul Gortmaker and Andries Brouwer |
2 | .\" | |
1dd72f9c | 3 | .\" %%%LICENSE_START(GPLv2+_DOC_FULL) |
fea681da MK |
4 | .\" This is free documentation; you can redistribute it and/or |
5 | .\" modify it under the terms of the GNU General Public License as | |
6 | .\" published by the Free Software Foundation; either version 2 of | |
7 | .\" the License, or (at your option) any later version. | |
8 | .\" | |
9 | .\" The GNU General Public License's references to "object code" | |
10 | .\" and "executables" are to be interpreted as the output of any | |
11 | .\" document formatting or typesetting system, including | |
12 | .\" intermediate and printed output. | |
13 | .\" | |
14 | .\" This manual is distributed in the hope that it will be useful, | |
15 | .\" but WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | .\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
17 | .\" GNU General Public License for more details. | |
18 | .\" | |
19 | .\" You should have received a copy of the GNU General Public | |
c715f741 MK |
20 | .\" License along with this manual; if not, see |
21 | .\" <http://www.gnu.org/licenses/>. | |
6a8d8745 | 22 | .\" %%%LICENSE_END |
fea681da MK |
23 | .\" |
24 | .\" This man page written 950814 by aeb, based on Paul Gortmaker's HOWTO | |
25 | .\" (dated v1.0.1, 15/08/95). | |
26 | .\" Major update, aeb, 970114. | |
27 | .\" | |
67d2c687 | 28 | .TH BOOTPARAM 7 2015-05-07 "Linux" "Linux Programmer's Manual" |
fea681da | 29 | .SH NAME |
f68512e9 | 30 | bootparam \- introduction to boot time parameters of the Linux kernel |
fea681da | 31 | .SH DESCRIPTION |
76c44d83 | 32 | The Linux kernel accepts certain 'command-line options' or 'boot time |
c13182ef | 33 | parameters' at the moment it is started. |
55a51edb | 34 | In general, this is used to |
fea681da MK |
35 | supply the kernel with information about hardware parameters that |
36 | the kernel would not be able to determine on its own, or to avoid/override | |
37 | the values that the kernel would otherwise detect. | |
38 | ||
ad8fe082 | 39 | When the kernel is booted directly by the BIOS, |
fea681da MK |
40 | you have no opportunity to specify any parameters. |
41 | So, in order to take advantage of this possibility you have to | |
122a101a | 42 | use a boot loader that is able to pass parameters, such as GRUB. |
73d8cece | 43 | .SS The argument list |
fea681da | 44 | The kernel command line is parsed into a list of strings |
c13182ef | 45 | (boot arguments) separated by spaces. |
36267a51 | 46 | Most of the boot arguments have the form: |
77bda21c MK |
47 | |
48 | .in +4n | |
49 | .nf | |
fea681da | 50 | name[=value_1][,value_2]...[,value_10] |
77bda21c MK |
51 | .fi |
52 | .in | |
fea681da | 53 | .LP |
40dedbfe | 54 | where 'name' is a unique keyword that is used to identify what part of |
fea681da | 55 | the kernel the associated values (if any) are to be given to. |
33a0ccb2 | 56 | Note the limit of 10 is real, as the present code handles only 10 comma |
c13182ef | 57 | separated parameters per keyword. |
3b777aff | 58 | (However, you can reuse the same |
fea681da MK |
59 | keyword with up to an additional 10 parameters in unusually |
60 | complicated situations, assuming the setup function supports it.) | |
61 | ||
e57fca5a MK |
62 | Most of the sorting is coded in the kernel source file |
63 | .IR init/main.c . | |
c13182ef | 64 | First, the kernel |
40dedbfe | 65 | checks to see if the argument is any of the special arguments 'root=', |
25715c96 | 66 | \&'nfsroot=', 'nfsaddrs=', 'ro', 'rw', 'debug' or 'init'. |
c13182ef | 67 | The meaning of these special arguments is described below. |
fea681da | 68 | |
b46a2f4a MK |
69 | Then it walks a list of setup functions |
70 | to see if the specified argument string (such as 'foo') has | |
40dedbfe | 71 | been associated with a setup function ('foo_setup()') for a particular |
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72 | device or part of the kernel. |
73 | If you passed the kernel the line | |
fea681da | 74 | foo=3,4,5,6 then the kernel would search the bootsetups array to see |
40dedbfe | 75 | if 'foo' was registered. |
c13182ef | 76 | If it was, then it would call the setup |
40dedbfe | 77 | function associated with 'foo' (foo_setup()) and hand it the arguments |
31df5734 | 78 | 3, 4, 5, and 6 as given on the kernel command line. |
fea681da | 79 | |
40dedbfe | 80 | Anything of the form 'foo=bar' that is not accepted as a setup function |
fea681da | 81 | as described above is then interpreted as an environment variable to |
c13182ef | 82 | be set. |
40dedbfe | 83 | A (useless?) example would be to use 'TERM=vt100' as a boot |
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84 | argument. |
85 | ||
86 | Any remaining arguments that were not picked up by the kernel and were | |
f184a1c3 MK |
87 | not interpreted as environment variables are then passed onto PID 1, |
88 | which is usually the | |
1aedd258 MK |
89 | .BR init (1) |
90 | program. | |
c13182ef | 91 | The most common argument that |
1aedd258 MK |
92 | is passed to the |
93 | .I init | |
94 | process is the word 'single' which instructs it | |
fea681da | 95 | to boot the computer in single user mode, and not launch all the usual |
c13182ef | 96 | daemons. |
1aedd258 MK |
97 | Check the manual page for the version of |
98 | .BR init (1) | |
99 | installed on | |
fea681da | 100 | your system to see what arguments it accepts. |
76c637e1 | 101 | .SS General non-device-specific boot arguments |
bebbbd1f | 102 | .TP |
40dedbfe | 103 | .B "'init=...'" |
fea681da MK |
104 | This sets the initial command to be executed by the kernel. |
105 | If this is not set, or cannot be found, the kernel will try | |
5ce89119 MK |
106 | .IR /sbin/init , |
107 | then | |
fea681da MK |
108 | .IR /etc/init , |
109 | then | |
110 | .IR /bin/init , | |
111 | then | |
0daa9e92 | 112 | .I /bin/sh |
fea681da | 113 | and panic if all of this fails. |
bebbbd1f | 114 | .TP |
40dedbfe | 115 | .B "'nfsaddrs=...'" |
32ae2e17 | 116 | This sets the NFS boot address to the given string. |
fea681da | 117 | This boot address is used in case of a net boot. |
bebbbd1f | 118 | .TP |
40dedbfe | 119 | .B "'nfsroot=...'" |
5d6aa84a | 120 | This sets the NFS root name to the given string. |
c13182ef | 121 | If this string |
fea681da | 122 | does not begin with '/' or ',' or a digit, then it is prefixed by |
25715c96 | 123 | \&'/tftpboot/'. |
c13182ef | 124 | This root name is used in case of a net boot. |
bebbbd1f | 125 | .TP |
40dedbfe | 126 | .B "'root=...'" |
fea681da | 127 | This argument tells the kernel what device is to be used as the root |
9ee4a2b6 | 128 | filesystem while booting. |
c13182ef | 129 | The default of this setting is determined |
fea681da | 130 | at compile time, and usually is the value of the root device of the |
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131 | system that the kernel was built on. |
132 | To override this value, and | |
fea681da | 133 | select the second floppy drive as the root device, one would |
6387216b | 134 | use 'root=/dev/fd1'. |
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135 | |
136 | The root device can be specified symbolically or numerically. | |
e57fca5a | 137 | A symbolic specification has the form |
21e79503 | 138 | .IR /dev/XXYN , |
e57fca5a | 139 | where XX designates |
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140 | the device type (e.g., 'hd' for ST-506 compatible hard disk, with Y in |
141 | \&'a'-'d'; 'sd' for SCSI compatible disk, with Y in 'a'-'e'), | |
142 | Y the driver letter or | |
143 | number, and N the number (in decimal) of the partition on this device. | |
fea681da MK |
144 | |
145 | Note that this has nothing to do with the designation of these | |
9ee4a2b6 | 146 | devices on your filesystem. |
40dedbfe | 147 | The '/dev/' part is purely conventional. |
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148 | |
149 | The more awkward and less portable numeric specification of the above | |
c13182ef | 150 | possible root devices in major/minor format is also accepted. |
59dc509c | 151 | (For example, |
e57fca5a MK |
152 | .I /dev/sda3 |
153 | is major 8, minor 3, so you could use 'root=0x803' as an | |
fea681da | 154 | alternative.) |
bebbbd1f | 155 | .TP |
1c137827 | 156 | .BR "'rootdelay='" |
91085d85 | 157 | This parameter sets the delay (in seconds) to pause before attempting |
1c137827 PG |
158 | to mount the root filesystem. |
159 | .TP | |
160 | .BR "'rootflags=...'" | |
ffe8d0b1 MK |
161 | This parameter sets the mount option string for the root filesystem |
162 | (see also | |
1c137827 PG |
163 | .BR fstab (5)). |
164 | .TP | |
6c8adf48 JLDL |
165 | .BR "'rootfstype=...'" |
166 | The 'rootfstype' option tells the kernel to mount the root filesystem as | |
167 | if it where of the type specified. | |
168 | This can be useful (for example) to | |
169 | mount an ext3 filesystem as ext2 and then remove the journal in the root | |
170 | filesystem, in fact reverting its format from ext3 to ext2 without the | |
171 | need to boot the box from alternate media. | |
172 | .TP | |
40dedbfe | 173 | .BR 'ro' " and " 'rw' |
9ee4a2b6 MK |
174 | The 'ro' option tells the kernel to mount the root filesystem |
175 | as 'read-only' so that filesystem consistency check programs (fsck) | |
176 | can do their work on a quiescent filesystem. | |
c13182ef | 177 | No processes can |
9ee4a2b6 | 178 | write to files on the filesystem in question until it is 'remounted' |
40dedbfe | 179 | as read/write capable, for example, by 'mount \-w \-n \-o remount /'. |
fea681da MK |
180 | (See also |
181 | .BR mount (8).) | |
182 | ||
9ee4a2b6 | 183 | The 'rw' option tells the kernel to mount the root filesystem read/write. |
fea681da | 184 | This is the default. |
bebbbd1f | 185 | .TP |
d11f367d AR |
186 | .B "'resume=...'" |
187 | This tells the kernel the location of the suspend-to-disk data that you want the machine to resume from after hibernation. | |
063692c0 MK |
188 | Usually, it is the same as your swap partition or file. |
189 | Example: | |
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190 | |
191 | .in +4n | |
192 | .nf | |
193 | resume=/dev/hda2 | |
194 | .fi | |
195 | .in | |
d11f367d | 196 | .TP |
40dedbfe | 197 | .B "'reserve=...'" |
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198 | This is used to protect I/O port regions from probes. |
199 | The form of the command is: | |
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200 | |
201 | .in +4n | |
202 | .nf | |
fea681da | 203 | .BI reserve= iobase,extent[,iobase,extent]... |
77bda21c MK |
204 | .fi |
205 | .in | |
bebbbd1f | 206 | .sp |
fea681da | 207 | In some machines it may be necessary to prevent device drivers from |
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208 | checking for devices (auto-probing) in a specific region. |
209 | This may be | |
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210 | because of hardware that reacts badly to the probing, or hardware |
211 | that would be mistakenly identified, or merely | |
212 | hardware you don't want the kernel to initialize. | |
213 | ||
214 | The reserve boot-time argument specifies an I/O port region that | |
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215 | shouldn't be probed. |
216 | A device driver will not probe a reserved region, | |
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217 | unless another boot argument explicitly specifies that it do so. |
218 | ||
219 | For example, the boot line | |
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220 | |
221 | .in +4n | |
222 | .nf | |
fea681da | 223 | reserve=0x300,32 blah=0x300 |
77bda21c MK |
224 | .fi |
225 | .in | |
bebbbd1f | 226 | .IP |
40dedbfe | 227 | keeps all device drivers except the driver for 'blah' from probing |
94e9d9fe | 228 | 0x300\-0x31f. |
bebbbd1f | 229 | .TP |
40dedbfe | 230 | .B "'panic=N'" |
b9aee8fe | 231 | By default, the kernel will not reboot after a panic, but this option |
f7ceac86 | 232 | will cause a kernel reboot after N seconds (if N is greater than zero). |
77bda21c MK |
233 | This panic timeout can also be set by |
234 | ||
235 | .in +4n | |
236 | .nf | |
1322e836 | 237 | echo N > /proc/sys/kernel/panic |
77bda21c MK |
238 | .fi |
239 | .in | |
bebbbd1f | 240 | .TP |
40dedbfe | 241 | .B "'reboot=[warm|cold][,[bios|hard]]'" |
66d2031a | 242 | Since Linux 2.0.22, a reboot is by default a cold reboot. |
40dedbfe | 243 | One asks for the old default with 'reboot=warm'. |
fea681da MK |
244 | (A cold reboot may be required to reset certain hardware, |
245 | but might destroy not yet written data in a disk cache. | |
246 | A warm reboot may be faster.) | |
b9aee8fe | 247 | By default, a reboot is hard, by asking the keyboard controller |
fea681da | 248 | to pulse the reset line low, but there is at least one type |
c13182ef | 249 | of motherboard where that doesn't work. |
40dedbfe | 250 | The option 'reboot=bios' will |
fea681da | 251 | instead jump through the BIOS. |
bebbbd1f | 252 | .TP |
40dedbfe | 253 | .BR 'nosmp' " and " 'maxcpus=N' |
fea681da | 254 | (Only when __SMP__ is defined.) |
40dedbfe MK |
255 | A command-line option of 'nosmp' or 'maxcpus=0' will disable SMP |
256 | activation entirely; an option 'maxcpus=N' limits the maximum number | |
fea681da | 257 | of CPUs activated in SMP mode to N. |
73d8cece | 258 | .SS Boot arguments for use by kernel developers |
bebbbd1f | 259 | .TP |
40dedbfe | 260 | .B "'debug'" |
016d2ca0 MK |
261 | Kernel messages are handed off to a daemon (e.g., |
262 | .BR klogd (8) | |
263 | or similar) so that they may be logged to disk. | |
c13182ef | 264 | Messages with a priority above |
fea681da | 265 | .I console_loglevel |
c13182ef | 266 | are also printed on the console. |
c14e2adc | 267 | (For a discussion of log levels, see |
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268 | .BR syslog (2).) |
269 | By default, | |
270 | .I console_loglevel | |
271 | is set to log messages at levels higher than | |
272 | .BR KERN_DEBUG . | |
c13182ef | 273 | This boot argument will cause the kernel to also |
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274 | print messages logged at level |
275 | .BR KERN_DEBUG . | |
276 | The console loglevel can also be set on a booted system via the | |
277 | .IR /proc/sys/kernel/printk | |
278 | file (described in | |
279 | .BR syslog (2)), | |
280 | the | |
281 | .BR syslog (2) | |
282 | .B SYSLOG_ACTION_CONSOLE_LEVEL | |
283 | operation, or | |
284 | .BR dmesg (8). | |
bebbbd1f | 285 | .TP |
40dedbfe | 286 | .B "'profile=N'" |
fea681da MK |
287 | It is possible to enable a kernel profiling function, |
288 | if one wishes to find out where the kernel is spending its CPU cycles. | |
289 | Profiling is enabled by setting the variable | |
290 | .I prof_shift | |
c7094399 | 291 | to a nonzero value. |
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292 | This is done either by specifying |
293 | .B CONFIG_PROFILE | |
294 | at compile time, or by giving the 'profile=' option. | |
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295 | Now the value that |
296 | .I prof_shift | |
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297 | gets will be N, when given, or |
298 | .BR CONFIG_PROFILE_SHIFT , | |
299 | when that is given, or 2, the default. | |
c13182ef | 300 | The significance of this variable is that it |
fea681da MK |
301 | gives the granularity of the profiling: each clock tick, if the |
302 | system was executing kernel code, a counter is incremented: | |
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303 | |
304 | .in +4n | |
305 | .nf | |
fea681da | 306 | profile[address >> prof_shift]++; |
77bda21c MK |
307 | .fi |
308 | .in | |
bebbbd1f | 309 | .sp |
fea681da MK |
310 | The raw profiling information can be read from |
311 | .IR /proc/profile . | |
312 | Probably you'll want to use a tool such as readprofile.c to digest it. | |
313 | Writing to | |
314 | .I /proc/profile | |
315 | will clear the counters. | |
73d8cece | 316 | .SS Boot arguments for ramdisk use |
40dedbfe MK |
317 | (Only if the kernel was compiled with |
318 | .BR CONFIG_BLK_DEV_RAM .) | |
5503c85e MK |
319 | In general it is a bad idea to use a ramdisk under Linux\(emthe |
320 | system will use available memory more efficiently itself. | |
1aa04a53 | 321 | But while booting, |
fea681da | 322 | it is often useful to load the floppy contents into a |
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323 | ramdisk. |
324 | One might also have a system in which first | |
9ee4a2b6 | 325 | some modules (for filesystem or hardware) must be loaded |
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326 | before the main disk can be accessed. |
327 | ||
328 | In Linux 1.3.48, ramdisk handling was changed drastically. | |
329 | Earlier, the memory was allocated statically, and there was | |
40dedbfe | 330 | a 'ramdisk=N' parameter to tell its size. |
421405f9 | 331 | (This could also be set in the kernel image at compile time.) |
fea681da | 332 | These days ram disks use the buffer cache, and grow dynamically. |
1aa04a53 | 333 | For a lot of information on the current ramdisk |
22367af2 | 334 | setup, see the kernel source file |
51700fd7 | 335 | .IR Documentation/blockdev/ramdisk.txt |
e57fca5a MK |
336 | .RI ( Documentation/ramdisk.txt |
337 | in older kernels). | |
fea681da MK |
338 | |
339 | There are four parameters, two boolean and two integral. | |
bebbbd1f | 340 | .TP |
40dedbfe | 341 | .B "'load_ramdisk=N'" |
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342 | If N=1, do load a ramdisk. |
343 | If N=0, do not load a ramdisk. | |
fea681da | 344 | (This is the default.) |
bebbbd1f | 345 | .TP |
40dedbfe | 346 | .B "'prompt_ramdisk=N'" |
c13182ef MK |
347 | If N=1, do prompt for insertion of the floppy. |
348 | (This is the default.) | |
349 | If N=0, do not prompt. | |
350 | (Thus, this parameter is never needed.) | |
bebbbd1f | 351 | .TP |
40dedbfe | 352 | .BR 'ramdisk_size=N' " or (obsolete) " 'ramdisk=N' |
c13182ef MK |
353 | Set the maximal size of the ramdisk(s) to N kB. |
354 | The default is 4096 (4 MB). | |
bebbbd1f | 355 | .TP |
40dedbfe | 356 | .B "'ramdisk_start=N'" |
fea681da MK |
357 | Sets the starting block number (the offset on the floppy where |
358 | the ramdisk starts) to N. | |
359 | This is needed in case the ramdisk follows a kernel image. | |
bebbbd1f | 360 | .TP |
40dedbfe MK |
361 | .B "'noinitrd'" |
362 | (Only if the kernel was compiled with | |
363 | .B CONFIG_BLK_DEV_RAM | |
364 | and | |
365 | .BR CONFIG_BLK_DEV_INITRD .) | |
fea681da MK |
366 | These days it is possible to compile the kernel to use initrd. |
367 | When this feature is enabled, the boot process will load the kernel | |
368 | and an initial ramdisk; then the kernel converts initrd into | |
369 | a "normal" ramdisk, which is mounted read-write as root device; | |
e57fca5a MK |
370 | then |
371 | .I /linuxrc | |
9ee4a2b6 MK |
372 | is executed; afterward the "real" root filesystem is mounted, |
373 | and the initrd filesystem is moved over to | |
e57fca5a MK |
374 | .IR /initrd ; |
375 | finally | |
376 | the usual boot sequence (e.g., invocation of | |
377 | .IR /sbin/init ) | |
378 | is performed. | |
fea681da | 379 | |
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380 | For a detailed description of the initrd feature, see the kernel source file |
381 | .IR Documentation/initrd.txt . | |
fea681da | 382 | |
40dedbfe | 383 | The 'noinitrd' option tells the kernel that although it was compiled for |
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384 | operation with initrd, it should not go through the above steps, but |
385 | leave the initrd data under | |
386 | .IR /dev/initrd . | |
4d9b6984 | 387 | (This device can be used only once: the data is freed as soon as |
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388 | the last process that used it has closed |
389 | .IR /dev/initrd .) | |
73d8cece | 390 | .SS Boot arguments for SCSI devices |
fea681da MK |
391 | General notation for this section: |
392 | ||
393 | .I iobase | |
c13182ef MK |
394 | -- the first I/O port that the SCSI host occupies. |
395 | These are specified in hexadecimal notation, | |
396 | and usually lie in the range from 0x200 to 0x3ff. | |
fea681da MK |
397 | |
398 | .I irq | |
399 | -- the hardware interrupt that the card is configured to use. | |
400 | Valid values will be dependent on the card in question, but will | |
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401 | usually be 5, 7, 9, 10, 11, 12, and 15. |
402 | The other values are usually | |
fea681da | 403 | used for common peripherals like IDE hard disks, floppies, serial |
fb3969cd | 404 | ports, and so on. |
fea681da MK |
405 | |
406 | .I scsi-id | |
407 | -- the ID that the host adapter uses to identify itself on the | |
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408 | SCSI bus. |
409 | Only some host adapters allow you to change this value, as | |
410 | most have it permanently specified internally. | |
411 | The usual default value | |
fea681da MK |
412 | is 7, but the Seagate and Future Domain TMC-950 boards use 6. |
413 | ||
414 | .I parity | |
415 | -- whether the SCSI host adapter expects the attached devices | |
c13182ef MK |
416 | to supply a parity value with all information exchanges. |
417 | Specifying a one indicates parity checking is enabled, | |
418 | and a zero disables parity checking. | |
419 | Again, not all adapters will support selection of parity | |
d9bfdb9c | 420 | behavior as a boot argument. |
bebbbd1f | 421 | .TP |
40dedbfe | 422 | .B "'max_scsi_luns=...'" |
310672d6 | 423 | A SCSI device can have a number of 'subdevices' contained within |
c13182ef MK |
424 | itself. |
425 | The most common example is one of the new SCSI CD-ROMs that | |
426 | handle more than one disk at a time. | |
427 | Each CD is addressed as a | |
25715c96 | 428 | \&'Logical Unit Number' (LUN) of that particular device. |
c13182ef | 429 | But most |
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430 | devices, such as hard disks, tape drives and such are only one device, |
431 | and will be assigned to LUN zero. | |
432 | ||
433 | Some poorly designed SCSI devices cannot handle being probed for | |
c13182ef | 434 | LUNs not equal to zero. |
29aceda4 | 435 | Therefore, if the compile-time flag |
40dedbfe | 436 | .B CONFIG_SCSI_MULTI_LUN |
e0a06014 | 437 | is not set, newer kernels will by default probe only LUN zero. |
fea681da MK |
438 | |
439 | To specify the number of probed LUNs at boot, one enters | |
25715c96 | 440 | \&'max_scsi_luns=n' as a boot arg, where n is a number between one and |
c13182ef MK |
441 | eight. |
442 | To avoid problems as described above, one would use n=1 to | |
fea681da | 443 | avoid upsetting such broken devices. |
bebbbd1f MK |
444 | .TP |
445 | .B "SCSI tape configuration" | |
fea681da MK |
446 | Some boot time configuration of the SCSI tape driver can be achieved |
447 | by using the following: | |
77bda21c MK |
448 | |
449 | .in +4n | |
450 | .nf | |
fea681da | 451 | .BI st= buf_size[,write_threshold[,max_bufs]] |
77bda21c MK |
452 | .fi |
453 | .in | |
bebbbd1f | 454 | .sp |
c13182ef MK |
455 | The first two numbers are specified in units of kB. |
456 | The default | |
fea681da MK |
457 | .I buf_size |
458 | is 32kB, and the maximum size that can be specified is a | |
c13182ef MK |
459 | ridiculous 16384kB. |
460 | The | |
fea681da MK |
461 | .I write_threshold |
462 | is the value at which the buffer is committed to tape, with a | |
c13182ef MK |
463 | default value of 30kB. |
464 | The maximum number of buffers varies | |
fea681da MK |
465 | with the number of drives detected, and has a default of two. |
466 | An example usage would be: | |
77bda21c MK |
467 | |
468 | .in +4n | |
469 | .nf | |
fea681da | 470 | st=32,30,2 |
77bda21c MK |
471 | .fi |
472 | .in | |
bebbbd1f | 473 | .IP |
4568d084 MK |
474 | Full details can be found in the file |
475 | .I Documentation/scsi/st.txt | |
476 | (or | |
477 | .I drivers/scsi/README.st | |
66a9882e | 478 | for older kernels) in the Linux kernel source. |
73d8cece | 479 | .SS Hard disks |
bebbbd1f MK |
480 | .TP |
481 | .B "IDE Disk/CD-ROM Driver Parameters" | |
fea681da | 482 | The IDE driver accepts a number of parameters, which range from disk |
c13182ef | 483 | geometry specifications, to support for broken controller chips. |
e2badfdf | 484 | Drive-specific options are specified by using 'hdX=' with X in 'a'-'h'. |
fea681da | 485 | |
e2badfdf MK |
486 | Non-drive-specific options are specified with the prefix 'hd='. |
487 | Note that using a drive-specific prefix for a non-drive-specific option | |
fea681da MK |
488 | will still work, and the option will just be applied as expected. |
489 | ||
40dedbfe | 490 | Also note that 'hd=' can be used to refer to the next unspecified |
c13182ef MK |
491 | drive in the (a, ..., h) sequence. |
492 | For the following discussions, | |
40dedbfe | 493 | the 'hd=' option will be cited for brevity. |
c13182ef | 494 | See the file |
0eb9025a | 495 | .I Documentation/ide/ide.txt |
4568d084 | 496 | (or |
0eb9025a MK |
497 | .I Documentation/ide.txt |
498 | .\" Linux 2.0, 2.2, 2.4 | |
499 | in older kernels, or | |
4568d084 | 500 | .I drivers/block/README.ide |
0eb9025a | 501 | in ancient kernels) in the Linux kernel source for more details. |
bebbbd1f | 502 | .TP |
40dedbfe | 503 | .B "The 'hd=cyls,heads,sects[,wpcom[,irq]]' options" |
fea681da | 504 | These options are used to specify the physical geometry of the disk. |
c13182ef MK |
505 | Only the first three values are required. |
506 | The cylinder/head/sectors | |
507 | values will be those used by fdisk. | |
508 | The write precompensation value | |
509 | is ignored for IDE disks. | |
510 | The IRQ value specified will be the IRQ | |
fea681da | 511 | used for the interface that the drive resides on, and is not really a |
e2badfdf | 512 | drive-specific parameter. |
bebbbd1f | 513 | .TP |
40dedbfe | 514 | .B "The 'hd=serialize' option" |
fea681da MK |
515 | The dual IDE interface CMD-640 chip is broken as designed such that |
516 | when drives on the secondary interface are used at the same time as | |
c13182ef MK |
517 | drives on the primary interface, it will corrupt your data. |
518 | Using this | |
fea681da MK |
519 | option tells the driver to make sure that both interfaces are never |
520 | used at the same time. | |
bebbbd1f | 521 | .TP |
40dedbfe | 522 | .B "The 'hd=noprobe' option" |
c13182ef MK |
523 | Do not probe for this drive. |
524 | For example, | |
77bda21c MK |
525 | |
526 | .in +4n | |
527 | .nf | |
fea681da | 528 | hdb=noprobe hdb=1166,7,17 |
77bda21c MK |
529 | .fi |
530 | .in | |
bebbbd1f | 531 | .IP |
fea681da MK |
532 | would disable the probe, but still specify the drive geometry so |
533 | that it would be registered as a valid block device, and hence | |
534 | usable. | |
bebbbd1f | 535 | .TP |
40dedbfe MK |
536 | .B "The 'hd=nowerr' option" |
537 | Some drives apparently have the | |
538 | .B WRERR_STAT | |
539 | bit stuck on permanently. | |
fea681da | 540 | This enables a work-around for these broken devices. |
bebbbd1f | 541 | .TP |
40dedbfe | 542 | .B "The 'hd=cdrom' option" |
fea681da | 543 | This tells the IDE driver that there is an ATAPI compatible CD-ROM |
c13182ef MK |
544 | attached in place of a normal IDE hard disk. |
545 | In most cases the CD-ROM | |
fea681da | 546 | is identified automatically, but if it isn't then this may help. |
bebbbd1f | 547 | .TP |
40dedbfe | 548 | .B "Standard ST-506 Disk Driver Options ('hd=')" |
fea681da | 549 | The standard disk driver can accept geometry arguments for the disks |
c13182ef | 550 | similar to the IDE driver. |
33a0ccb2 | 551 | Note however that it expects only three |
c13182ef | 552 | values (C/H/S); any more or any less and it will silently ignore you. |
33a0ccb2 | 553 | Also, it accepts only 'hd=' as an argument, that is, 'hda=' |
c13182ef MK |
554 | and so on are not valid here. |
555 | The format is as follows: | |
77bda21c MK |
556 | |
557 | .in +4n | |
558 | .nf | |
fea681da | 559 | hd=cyls,heads,sects |
77bda21c MK |
560 | .fi |
561 | .in | |
bebbbd1f | 562 | .IP |
fea681da MK |
563 | If there are two disks installed, the above is repeated with the |
564 | geometry parameters of the second disk. | |
73d8cece | 565 | .SS Ethernet devices |
fea681da | 566 | Different drivers make use of different parameters, but they all at |
c13182ef MK |
567 | least share having an IRQ, an I/O port base value, and a name. |
568 | In its most generic form, it looks something like this: | |
77bda21c MK |
569 | |
570 | .in +4n | |
571 | .nf | |
fea681da | 572 | ether=irq,iobase[,param_1[,...param_8]],name |
77bda21c MK |
573 | .fi |
574 | .in | |
575 | ||
80c9146c | 576 | The first nonnumeric argument is taken as the name. |
c13182ef MK |
577 | The param_n values (if applicable) usually have different meanings for each |
578 | different card/driver. | |
579 | Typical param_n values are used to specify | |
fea681da MK |
580 | things like shared memory address, interface selection, DMA channel |
581 | and the like. | |
582 | ||
583 | The most common use of this parameter is to force probing for a second | |
33a0ccb2 | 584 | ethercard, as the default is to probe only for one. |
c13182ef | 585 | This can be accomplished with a simple: |
77bda21c MK |
586 | |
587 | .in +4n | |
588 | .nf | |
fea681da | 589 | ether=0,0,eth1 |
77bda21c MK |
590 | .fi |
591 | .in | |
592 | ||
fea681da MK |
593 | Note that the values of zero for the IRQ and I/O base in the above |
594 | example tell the driver(s) to autoprobe. | |
595 | ||
596 | The Ethernet-HowTo has extensive documentation on using multiple | |
e2badfdf | 597 | cards and on the card/driver-specific implementation |
c13182ef MK |
598 | of the param_n values where used. |
599 | Interested readers should refer to | |
fea681da | 600 | the section in that document on their particular card. |
73d8cece | 601 | .SS The floppy disk driver |
fea681da | 602 | There are many floppy driver options, and they are all listed in |
cb6cb860 | 603 | .I Documentation/blockdev/floppy.txt |
4568d084 | 604 | (or |
cb6cb860 | 605 | .I Documentation/floppy.txt |
dada4047 | 606 | in older kernels, or |
4568d084 | 607 | .I drivers/block/README.fd |
cb6cb860 | 608 | for ancient kernels) in the Linux kernel source. |
3dd80946 | 609 | See that file for the details. |
73d8cece | 610 | .SS The sound driver |
92b451e5 | 611 | The sound driver can also accept boot arguments to override the compiled-in |
c13182ef MK |
612 | values. |
613 | This is not recommended, as it is rather complex. | |
66a9882e | 614 | It is described in the Linux kernel source file |
ef505ff0 MK |
615 | .IR Documentation/sound/oss/README.OSS |
616 | .RI ( drivers/sound/Readme.linux | |
617 | in older kernel versions). | |
c13182ef | 618 | It accepts |
77bda21c MK |
619 | a boot argument of the form: |
620 | ||
621 | .in +4n | |
622 | .nf | |
fea681da | 623 | sound=device1[,device2[,device3...[,device10]]] |
77bda21c MK |
624 | .fi |
625 | .in | |
bebbbd1f | 626 | .IP |
fea681da MK |
627 | where each deviceN value is of the following format 0xTaaaId and the |
628 | bytes are used as follows: | |
629 | ||
4d9b6984 | 630 | T \- device type: 1=FM, 2=SB, 3=PAS, 4=GUS, 5=MPU401, 6=SB16, |
fea681da MK |
631 | 7=SB16-MPU401 |
632 | ||
4d9b6984 | 633 | aaa \- I/O address in hex. |
fea681da | 634 | |
658a3012 | 635 | I \- interrupt line in hex (i.e., 10=a, 11=b, ...) |
fea681da | 636 | |
4d9b6984 | 637 | d \- DMA channel. |
fea681da | 638 | |
92b451e5 | 639 | As you can see, it gets pretty messy, and you are better off to compile |
c13182ef | 640 | in your own personal values as recommended. |
77bda21c | 641 | Using a boot argument of |
25715c96 | 642 | \&'sound=0' will disable the sound driver entirely. |
73d8cece | 643 | .SS The line printer driver |
bebbbd1f | 644 | .TP |
40dedbfe | 645 | .B "'lp='" |
77bda21c | 646 | .br |
fea681da | 647 | Syntax: |
77bda21c MK |
648 | |
649 | .in +4n | |
650 | .nf | |
fea681da | 651 | lp=0 |
fea681da | 652 | lp=auto |
fea681da | 653 | lp=reset |
fea681da | 654 | lp=port[,port...] |
77bda21c MK |
655 | .fi |
656 | .in | |
bebbbd1f | 657 | .IP |
fea681da | 658 | You can tell the printer driver what ports to use and what ports not |
c13182ef MK |
659 | to use. |
660 | The latter comes in handy if you don't want the printer driver | |
fea681da | 661 | to claim all available parallel ports, so that other drivers |
75b94dc3 | 662 | (e.g., PLIP, PPA) can use them instead. |
fea681da | 663 | |
c13182ef MK |
664 | The format of the argument is multiple port names. |
665 | For example, | |
fea681da | 666 | lp=none,parport0 would use the first parallel port for lp1, and |
c13182ef MK |
667 | disable lp0. |
668 | To disable the printer driver entirely, one can use | |
fea681da | 669 | lp=0. |
fd7f0a7f MK |
670 | .\" .SH AUTHORS |
671 | .\" Linus Torvalds (and many others) | |
47297adb | 672 | .SH SEE ALSO |
fea681da | 673 | .BR klogd (8), |
421405f9 | 674 | .BR mount (8) |
fea681da | 675 | |
c7c19fcd | 676 | For up-to-date information, see the kernel source file |
e57fca5a | 677 | .IR Documentation/kernel-parameters.txt . |