Specifications

The `profile=' Argument
Kernel developers can profile how and where the kernel is spending its CPU cycles in an effort to maximize
efficiency and performance. This option lets you set the profile shift count at boot. Typically it is set to two.
You need a tool such as readprofile.c that can make use of the /proc/profile output.
The `quiet' Argument
This is pretty much the opposite of the `debug' argument. When this is given, only important and system
critical kernel messages are printed to the console. Normal messages about hardware detection at boot are
suppressed.
The `raid=' Argument
Accepts noautodetect at the moment. See also md=.
The `reboot=' Argument
This option controls the type of reboot that Linux will do when it resets the computer (typically via
/sbin/init handling a Control−Alt−Delete). The default as of v2.0 kernels is to do a `cold' reboot (i.e. full
reset, BIOS does memory check, etc.) instead of a `warm' reboot (i.e. no full reset, no memory check). It was
changed to be cold by default since that tends to work on cheap/broken hardware that fails to reboot when a
warm reboot is requested. To get the old behaviour (i.e. warm reboots) use reboot=w or in fact any word
that starts with w will work.
Other accepted options are `c', `b', `h', and `s', for cold, bios, hard, and SMP respectively. The `s' takes an
optional digit to specify which CPU should handle the reboot. Options can be combined where it makes sense,
i.e. reboot=b,s2
The `reserve=' Argument
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 poorly designed hardware that causes the boot to freeze (such as some
ethercards), hardware that is mistakenly identified, hardware whose state is changed by an earlier probe, or
merely hardware you don't want the kernel to initialize.
The reserve boot−time argument addresses this problem by specifying an I/O port region that shouldn't be
probed. That region is reserved in the kernel's port registration table as if a device has already been found in
that region (with the name reserved). Note that this mechanism shouldn't be necessary on most machines.
Only when there is a problem or special case would it be necessary to use this.
The I/O ports in the specified region are protected against device probes that do a check_region() prior
to probing blindly into a region of I/O space. This was put in to be used when some driver was hanging on a
NE2000, or misidentifying some other device as its own. A correct device driver shouldn't probe a reserved
region, unless another boot argument explicitly specifies that it do so. This implies that reserve will most
The Linux BootPrompt−HowTo
The `profile=' Argument 17