linux-kernel - Re: [PATCH] x86/PCI: initialize PCI bus node numbers early

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Message-ID: <4A9D5206.5010603@kernel.org>
Date:	Tue, 01 Sep 2009 09:55:34 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
	Jesse Brandeburg <jesse.brandeburg@...il.com>
Subject: Re: [PATCH] x86/PCI: initialize PCI bus node numbers early

Ingo Molnar wrote:
> * Jesse Barnes <jbarnes@...tuousgeek.org> wrote:
> 
>> The current mp_bus_to_node array is initialized only by AMD specific
>> code, since AMD platforms have registers that can be used for
>> determining mode numbers.  On new Intel platforms it's necessary to
>> initialize this array as well though, otherwise all PCI node numbers
>> will be 0, when in fact they should be -1 (indicating that I/O isn't
>> tied to any particular node).
>>
>> So move the mp_bus_to_node code into the common PCI code, and
>> initialize it early with a default value of -1.  This may be overridden
>> later by arch code (e.g. the AMD code).
>>
>> With this change, PCI consistent memory and other node specific
>> allocations (e.g. skbuff allocs) should occur on the "current" node.
>> If, for performance reasons, applications want to be bound to specific
>> nodes, they should open their devices only after being pinned to the
>> CPU where they'll run, for maximum locality.
>>
>> Any thoughts here Yinghai or Jesse?
>>
>>
>>  include/asm/pci.h |    2 +
>>  kernel/setup.c    |    2 +
>>  pci/amd_bus.c     |   61 +-----------------------------------------
>>  pci/common.c      |   77 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>  4 files changed, 83 insertions(+), 59 deletions(-)
> 
> FYI, this commit:
> 
>   acccaba: x86/PCI: initialize PCI bus node numbers early
> 
> caused a boot crash in -tip testing:
> 

looks like the patch change default 0 in 32bit to -1 ...

YH
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