Messages in this thread Patch in this message | | | Date | Mon, 6 Oct 2008 17:39:02 -0700 | From | Greg KH <> | Subject | [patch 38/71] x86: fix memmap=exactmap boot argument |
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2.6.26-stable review patch. If anyone has any objections, please let us know.
------------------ From: Prarit Bhargava <prarit@redhat.com>
Backport of d6be118a97ce51ca84035270f91c2bccecbfac5f by Chuck Ebbert
When using kdump modifying the e820 map is yielding strange results.
For example starting with
BIOS-provided physical RAM map: BIOS-e820: 0000000000000100 - 0000000000093400 (usable) BIOS-e820: 0000000000093400 - 00000000000a0000 (reserved) BIOS-e820: 0000000000100000 - 000000003fee0000 (usable) BIOS-e820: 000000003fee0000 - 000000003fef3000 (ACPI data) BIOS-e820: 000000003fef3000 - 000000003ff80000 (ACPI NVS) BIOS-e820: 000000003ff80000 - 0000000040000000 (reserved) BIOS-e820: 00000000e0000000 - 00000000f0000000 (reserved) BIOS-e820: 00000000fec00000 - 00000000fec10000 (reserved) BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved) BIOS-e820: 00000000ff000000 - 0000000100000000 (reserved)
and booting with args
memmap=exactmap memmap=640K@0K memmap=5228K@16384K memmap=125188K@22252K memmap=76K#1047424K memmap=564K#1047500K
resulted in:
user-defined physical RAM map: user: 0000000000000000 - 0000000000093400 (usable) user: 0000000000093400 - 00000000000a0000 (reserved) user: 0000000000100000 - 000000003fee0000 (usable) user: 000000003fee0000 - 000000003fef3000 (ACPI data) user: 000000003fef3000 - 000000003ff80000 (ACPI NVS) user: 000000003ff80000 - 0000000040000000 (reserved) user: 00000000e0000000 - 00000000f0000000 (reserved) user: 00000000fec00000 - 00000000fec10000 (reserved) user: 00000000fee00000 - 00000000fee01000 (reserved) user: 00000000ff000000 - 0000000100000000 (reserved)
But should have resulted in:
user-defined physical RAM map: user: 0000000000000000 - 00000000000a0000 (usable) user: 0000000001000000 - 000000000151b000 (usable) user: 00000000015bb000 - 0000000008ffc000 (usable) user: 000000003fee0000 - 000000003ff80000 (ACPI data)
This is happening because of an improper usage of strcmp() in the e820 parsing code. The strcmp() always returns !0 and never resets the value for e820.nr_map and returns an incorrect user-defined map.
This patch fixes the problem.
Signed-off-by: Prarit Bhargava <prarit@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Chuck Ebbert <cebbert@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- arch/x86/kernel/e820_32.c | 2 +- arch/x86/kernel/e820_64.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)
--- a/arch/x86/kernel/e820_32.c +++ b/arch/x86/kernel/e820_32.c @@ -697,7 +697,7 @@ static int __init parse_memmap(char *arg if (!arg) return -EINVAL; - if (strcmp(arg, "exactmap") == 0) { + if (strncmp(arg, "exactmap", 8) == 0) { #ifdef CONFIG_CRASH_DUMP /* If we are doing a crash dump, we * still need to know the real mem --- a/arch/x86/kernel/e820_64.c +++ b/arch/x86/kernel/e820_64.c @@ -776,7 +776,7 @@ static int __init parse_memmap_opt(char char *oldp; unsigned long long start_at, mem_size; - if (!strcmp(p, "exactmap")) { + if (!strncmp(p, "exactmap", 8)) { #ifdef CONFIG_CRASH_DUMP /* * If we are doing a crash dump, we still need to know --
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