Commit 5f5609df authored by Eric W. Biederman's avatar Eric W. Biederman Committed by Linus Torvalds
Browse files

[PATCH] crashdump: x86_64: crashkernel option 



This is the x86_64 implementation of the crashkernel option.  It reserves
a window of memory very early in the bootup process, so we never use
it for anything but the kernel to switch to when the running
kernel panics.

In addition to reserving this memory a resource structure is registered
so looking at /proc/iomem it is clear what happened to that memory.

ISSUES:
Is it possible to implement this in a architecture generic way?
What should be done with architectures that always use an iommu and
thus don't report their RAM memory resources in /proc/iomem?

Signed-off-by: default avatarEric Biederman <ebiederm@xmission.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 5234f5eb

arch/x86_64/kernel/e820.c

+4 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include <linux/bootmem.h>

#include <linux/ioport.h>

#include <linux/string.h>

#include <linux/kexec.h>

#include <asm/page.h>

#include <asm/e820.h>

#include <asm/proto.h>
@@ -210,6 +211,9 @@ void __init e820_reserve_resources(void) 
			 */

			request_resource(res, &code_resource);

			request_resource(res, &data_resource);

#ifdef CONFIG_KEXEC

			request_resource(res, &crashk_res);

#endif

		}

	}

}

arch/x86_64/kernel/setup.c

+29 −0
Original line number Diff line number Diff line
@@ -41,6 +41,7 @@ 
#include <linux/kallsyms.h>

#include <linux/edd.h>

#include <linux/mmzone.h>

#include <linux/kexec.h>



#include <asm/mtrr.h>

#include <asm/uaccess.h>
@@ -367,6 +368,27 @@ static __init void parse_cmdline_early (char ** cmdline_p) 
		if (!memcmp(from, "noexec=", 7))

			nonx_setup(from + 7);



#ifdef CONFIG_KEXEC

		/* crashkernel=size@addr specifies the location to reserve for

		 * a crash kernel.  By reserving this memory we guarantee

		 * that linux never set's it up as a DMA target.

		 * Useful for holding code to do something appropriate

		 * after a kernel panic.

		 */

		else if (!memcmp(from, "crashkernel=", 12)) {

			unsigned long size, base;

			size = memparse(from+12, &from);

			if (*from == '@') {

				base = memparse(from+1, &from);

				/* FIXME: Do I want a sanity check

				 * to validate the memory range?

				 */

				crashk_res.start = base;

				crashk_res.end   = base + size - 1;

			}

		}

#endif



	next_char:

		c = *(from++);

		if (!c)
@@ -625,6 +647,13 @@ void __init setup_arch(char **cmdline_p) 
#endif



	sparse_init();



#ifdef CONFIG_KEXEC

	if (crashk_res.start != crashk_res.end) {

		reserve_bootmem(crashk_res.start,

			crashk_res.end - crashk_res.start + 1);

	}

#endif

	paging_init();



	check_ioapic();

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