From 7e96287ddc4f42081e18248b6167041c0908004c Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Wed, 27 Sep 2006 01:50:44 -0700 Subject: [PATCH] [PATCH] kdump: introduce "reset_devices" command line option Resetting the devices during driver initialization can be a costly operation in terms of time (especially scsi devices). This option can be used by drivers to know that user forcibly wants the devices to be reset during initialization. This option can be useful while kernel is booting in unreliable environment. For ex. during kdump boot where devices are in unknown random state and BIOS execution has been skipped. Signed-off-by: Vivek Goyal Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/kernel-parameters.txt | 3 +++ include/linux/init.h | 1 + init/main.c | 20 ++++++++++++++++++++ 3 files changed, 24 insertions(+) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 255ec53..5498324 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1370,6 +1370,9 @@ running once the system is up. Reserves a hole at the top of the kernel virtual address space. + reset_devices [KNL] Force drivers to reset the underlying device + during initialization. + resume= [SWSUSP] Specify the partition device for software suspend diff --git a/include/linux/init.h b/include/linux/init.h index 6667785..e92b145 100644 --- a/include/linux/init.h +++ b/include/linux/init.h @@ -68,6 +68,7 @@ extern initcall_t __security_initcall_start[], __security_initcall_end[]; /* Defined in init/main.c */ extern char saved_command_line[]; +extern unsigned int reset_devices; /* used by init/main.c */ extern void setup_arch(char **); diff --git a/init/main.c b/init/main.c index 913e48d..0766e69 100644 --- a/init/main.c +++ b/init/main.c @@ -128,6 +128,18 @@ static char *ramdisk_execute_command; static unsigned int max_cpus = NR_CPUS; /* + * If set, this is an indication to the drivers that reset the underlying + * device before going ahead with the initialization otherwise driver might + * rely on the BIOS and skip the reset operation. + * + * This is useful if kernel is booting in an unreliable environment. + * For ex. kdump situaiton where previous kernel has crashed, BIOS has been + * skipped and devices will be in unknown state. + */ +unsigned int reset_devices; +EXPORT_SYMBOL(reset_devices); + +/* * Setup routine for controlling SMP activation * * Command-line option of "nosmp" or "maxcpus=0" will disable SMP @@ -153,6 +165,14 @@ static int __init maxcpus(char *str) __setup("maxcpus=", maxcpus); +static int __init set_reset_devices(char *str) +{ + reset_devices = 1; + return 1; +} + +__setup("reset_devices", set_reset_devices); + static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, }; char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, }; static const char *panic_later, *panic_param; -- 2.7.4