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SubjectRe: [REGRESSION] _end symbol missing from Symbol.map
Andrew Morton wrote:
> On Thu, 13 Aug 2009 08:45:20 +0200 Hannes Reinecke <hare@suse.de> wrote:
>
>> Hi all,
>>
>> with 2.6.31 'crash' on x86_64 falls flat on its face as the '_end' symbol
>> is missing from the System.map file.
>>
>> The culprit is commit 091e52c3551d3031343df24b573b770b4c6c72b6,
>> which moved the '_end' symbol into it's own section.
>> Apparently this causes kallsyms to not reference it properly.
>>
>> So either we'd need to revert part of the patch to not
>> include _end in it's own section:
>>
>> diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
>> index 59f31d2..1422df5 100644
>> --- a/arch/x86/kernel/vmlinux.lds.S
>> +++ b/arch/x86/kernel/vmlinux.lds.S
>> @@ -376,9 +376,7 @@ SECTIONS
>> __brk_limit = .;
>> }
>>
>> - .end : AT(ADDR(.end) - LOAD_OFFSET) {
>> - _end = .;
>> - }
>> + _end = .;
>>
>> /* Sections to be discarded */
>> /DISCARD/ : {
>>
>> or someone has to fixup kallsyms. But this is far beyond my comfort zone.
>>
>
> So System.map is part of the kernel API too? Sigh.
>
> Your email client replaces tabs with spaces.
>
I know.

> The patch didn't have a signed-off-by:
>
I know, too.
However, this is clearly a band-aid, and as such I reported
it more as an RFC.
One (Sam?) should really fix up kallsyms to extract the _end symbol.
Hence I didn't warrant it with a Signed-off line.

> I queued it up, and tagged it for -stable backporting. Unless we come
> up with something better.
>
I was sort of hoping Sam would speak up and present some better approach ...

> We might not get this into 2.6.31, in which case this fix or its
> replacement will need backporting to 2.6.30.x and 2.6.31.x (IMO).
>
Thanks for the feedback.

Cheers,

Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare@suse.de +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Markus Rex, HRB 16746 (AG Nürnberg)
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