Commit 7e96287d authored by Vivek Goyal's avatar Vivek Goyal Committed by Linus Torvalds
Browse files

[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: default avatarVivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent bcdc5e01

Documentation/kernel-parameters.txt

+3 −0
Original line number Diff line number Diff line
@@ -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

include/linux/init.h

+1 −0
Original line number Diff line number Diff line
@@ -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 **);

init/main.c

+20 −0
Original line number Diff line number Diff line
@@ -127,6 +127,18 @@ static char *ramdisk_execute_command; 
/* Setup configured maximum number of CPUs to activate */

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

 *
@@ -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;

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