Documentation/admin-guide/kernel-parameters.rst

3 The kernel's command-line parameters
12 The kernel parses parameters from the kernel command line up to "``--``";
13 if it doesn't recognize a parameter and it doesn't contain a '.', the
14 parameter gets passed to init: parameters with '=' go into init's
16 Everything after "``--``" is passed as an argument to init.
30 Hyphens (dashes) and underscores are equivalent in parameter names, so::
32 	log_buf_len=1M print-fatal-signals=1
36 	log-buf-len=1M print_fatal_signals=1
38 Double-quotes can be used to protect spaces in values, e.g.::
43 ----------
52 	<cpu number>-<cpu number>
57 <cpu number>,...,<cpu number>-<cpu number>
63 	<cpu number>-<cpu number>:<used size>/<group size>
65 For example one can add to the command line following parameter:
67 	isolcpus=1,2,10-20,100-2000:2/25
72 i.e "foo_cpus=16-N" would be equivalent to "16-31" on a 32 core system.
75 to change, such as less cores in the CPU list, then N and any ranges using N
76 will also change.  Use the same on a small 4 core system, and "16-N" becomes
77 "16-3" and now the same boot input will be flagged as invalid (start > end).
79 The special case-tolerant group name "all" has a meaning of selecting all CPUs,
80 so that "nohz_full=all" is the equivalent of "nohz_full=0-N".
86 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
90 ``echo -n ${value} > /sys/module/${modulename}/parameters/${parm}``.
95 of each description states the restrictions within which a parameter
111 	EARLY	Parameter processed too early to be embedded in initrd.
136 			Documentation/arch/m68k/kernel-options.rst.
146 	PARISC	The PA-RISC architecture is enabled.
161 			the Documentation/scsi/ sub-directory.
179 	X86-32	X86-32, aka i386 architecture is enabled.
180 	X86-64	X86-64 architecture is enabled.
181 			More X86-64 boot options can be found in
182 			Documentation/arch/x86/x86_64/boot-options.rst.
183 	X86	Either 32-bit or 64-bit x86 (same as X86-32+X86-64)
190 	BOOT	Is a boot loader parameter.
192 	KNL	Is a kernel start-up parameter.
199 There are also arch-specific kernel-parameters not documented here.
200 See for example <Documentation/arch/x86/x86_64/boot-options.rst>.
203 a trailing = on the name of any parameter states that that parameter will
212 ./include/uapi/asm-generic/setup.h as COMMAND_LINE_SIZE.
215 parameter values. These 'K', 'M', and 'G' letters represent the _binary_
219 .. include:: kernel-parameters.txt