On Thu, 2 Nov 2006, Magnus Damm wrote:
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().
Hey Magnus,
I see what you are doing and why. However if you look in
arch/x86_64/kernel/setup.c, you'll see
parse_early_param();
finish_e820_parsing();
e820_register_active_regions(0, 0, -1UL);
If you just called e820_register_active_regions(0, 0, -1UL) before
parse_early_param(), would it still fix the problem without having to call
e820_register_active_regions(0, 0, -1UL) twice?
Signed-off-by: Magnus Damm <[email protected]>
---
Applies to 2.6.19-rc4.
arch/x86_64/kernel/e820.c | 2 ++
1 file changed, 2 insertions(+)
--- 0002/arch/x86_64/kernel/e820.c
+++ work/arch/x86_64/kernel/e820.c 2006-11-02 21:37:19.000000000 +0900
@@ -594,7 +594,9 @@ static int __init parse_memmap_opt(char
* 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();
#endif
end_pfn_map = 0;
e820.nr_map = 0;
--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab
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