linux-kernel - Re: [tip:core/memblock] x86-64: Only set max_pfn_mapped to 512 MiB if we enter via head

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Date:	Wed, 13 Oct 2010 23:07:30 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Ingo Molnar <mingo@...e.hu>
CC:	mingo@...hat.com, hpa@...or.com, jeremy@...p.org,
	linux-kernel@...r.kernel.org, tglx@...utronix.de,
	hpa@...ux.intel.com, jeremy.fitzhardinge@...rix.com,
	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:core/memblock] x86-64: Only set max_pfn_mapped to 512 MiB
 if we enter via head_64.S

On 10/13/2010 10:57 PM, Ingo Molnar wrote:
> 
> * tip-bot for Jeremy Fitzhardinge <jeremy@...p.org> wrote:
> 
>> Commit-ID:  859ee4f57fb4e91de8439496f62eb996f4a28ca8
>> Gitweb:     http://git.kernel.org/tip/859ee4f57fb4e91de8439496f62eb996f4a28ca8
>> Author:     Jeremy Fitzhardinge <jeremy@...p.org>
>> AuthorDate: Wed, 13 Oct 2010 16:34:15 -0700
>> Committer:  H. Peter Anvin <hpa@...ux.intel.com>
>> CommitDate: Wed, 13 Oct 2010 17:09:59 -0700
>>
>> x86-64: Only set max_pfn_mapped to 512 MiB if we enter via head_64.S
>>
>> head_64.S maps up to 512 MiB, but that is not necessarity true for
>> other entry paths, such as Xen.
> 
> These two commits are a boot crasher on x86 defconfig (64-bit):
> 
> [    0.000000] init_memory_mapping: 0000000000000000-000000003fff0000
> [    0.000000]  0000000000 - 003fe00000 page 2M
> [    0.000000]  003fe00000 - 003fff0000 page 4k
> [    0.000000] Kernel panic - not syncing: Cannot find space for the kernel page tables
> [    0.000000] Pid: 0, comm: swapper Not tainted 2.6.36-rc7-tip+ #49192
> [    0.000000] Call Trace:
> [    0.000000]  [<ffffffff8156c73f>] panic+0x8c/0x192
> [    0.000000]  [<ffffffff8156c881>] ? printk+0x3c/0x3e
> [    0.000000]  [<ffffffff8154ec40>] init_memory_mapping+0x372/0x506
> [    0.000000]  [<ffffffff819053ed>] ? memblock_x86_reserve_range+0x7c/0x83
> [    0.000000]  [<ffffffff818f2f3d>] setup_arch+0x5a3/0xa68
> [    0.000000]  [<ffffffff8156c881>] ? printk+0x3c/0x3e
> [    0.000000]  [<ffffffff81061135>] ? clockevents_register_notifier+0x3e/0x4a
> [    0.000000]  [<ffffffff818ef9e1>] start_kernel+0x83/0x36e
> [    0.000000]  [<ffffffff818ef2a8>] x86_64_start_reservations+0xb8/0xbc
> [    0.000000]  [<ffffffff818ef393>] x86_64_start_kernel+0xe7/0xee

max_pfn_mapped is in .bss section. so it get cleared.

will have a patch to move clear_bss from head64.c to head_64.S

Thanks

Yinghai
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