From 5888bcc5d24acf911c3d12719d72968c9b27a02f Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Wed, 14 May 2014 10:33:45 +0930 Subject: [PATCH] Documentation: Update kernel-parameters.tx 1) __setup() is messy, prefer module_param and core_param. 2) Document -- 3) Document modprobe scraping /proc/cmdline. 4) Document handing of leftover parameters to init. 5) Document use of quotes to protect whitespace. Reported-by: Andrew Morton Signed-off-by: Rusty Russell --- Documentation/kernel-parameters.txt | 32 +++++++++++++++++++---------- 1 file changed, 21 insertions(+), 11 deletions(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 43842177b771..a42b9dd6b46b 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1,27 +1,37 @@ Kernel Parameters ~~~~~~~~~~~~~~~~~ -The following is a consolidated list of the kernel parameters as implemented -(mostly) by the __setup() macro and sorted into English Dictionary order -(defined as ignoring all punctuation and sorting digits before letters in a -case insensitive manner), and with descriptions where known. +The following is a consolidated list of the kernel parameters as +implemented by the __setup(), core_param() and module_param() macros +and sorted into English Dictionary order (defined as ignoring all +punctuation and sorting digits before letters in a case insensitive +manner), and with descriptions where known. -Module parameters for loadable modules are specified only as the -parameter name with optional '=' and value as appropriate, such as: +The kernel parses parameters from the kernel command line up to "--"; +if it doesn't recognize a parameter and it doesn't contain a '.', the +parameter gets passed to init: parameters with '=' go into init's +environment, others are passed as command line arguments to init. +Everything after "--" is passed as an argument to init. - modprobe usbcore blinkenlights=1 +Module parameters can be specified in two ways: via the kernel command +line with a module name prefix, or via modprobe, e.g.: -Module parameters for modules that are built into the kernel image -are specified on the kernel command line with the module name plus -'.' plus parameter name, with '=' and value if appropriate, such as: + (kernel command line) usbcore.blinkenlights=1 + (modprobe command line) modprobe usbcore blinkenlights=1 - usbcore.blinkenlights=1 +Parameters for modules which are built into the kernel need to be +specified on the kernel command line. modprobe looks through the +kernel command line (/proc/cmdline) and collects module parameters +when it loads a module, so the kernel command line can be used for +loadable modules too. Hyphens (dashes) and underscores are equivalent in parameter names, so log_buf_len=1M print-fatal-signals=1 can also be entered as log-buf-len=1M print_fatal_signals=1 +Double-quotes can be used to protect spaces in values, e.g.: + param="spaces in here" This document may not be entirely up to date and comprehensive. The command "modinfo -p ${modulename}" shows a current list of all parameters of a loadable