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[PATCH] x86-64: setup saved_max_pfn correctly (kdump)

x86_64: setup saved_max_pfn correctly

2.6.19-rc4 has broken CONFIG_CRASH_DUMP support on x86_64. It is impossible
to read out the kernel contents from /proc/vmcore because saved_max_pfn is set
to zero instead of the max_pfn value before the user map is setup.

This happens because saved_max_pfn is initialized at parse_early_param() time,
and at this time no active regions have been registered. save_max_pfn is setup
from e820_end_of_ram(), more exact find_max_pfn_with_active_regions() which
returns 0 because no regions exist.

This patch fixes this by registering before and removing after the call
to e820_end_of_ram().

Signed-off-by: Magnus Damm <>
Signed-off-by: Andi Kleen <>
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1 parent 5e58a02 commit 15803a43288da434d34d41c4ed650c3c1728d42c Magnus Damm committed with Andi Kleen Nov 14, 2006
Showing with 2 additions and 0 deletions.
  1. +2 −0 arch/x86_64/kernel/e820.c
2 arch/x86_64/kernel/e820.c
@@ -594,7 +594,9 @@ static int __init parse_memmap_opt(char *p)
* size before original memory map is
* reset.
+ e820_register_active_regions(0, 0, -1UL);
saved_max_pfn = e820_end_of_ram();
+ remove_all_active_ranges();
end_pfn_map = 0;
e820.nr_map = 0;

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