Re: [patch] x86: 2.6.31-rc7 crash due to buggy flat_phys_pkg_id

From: Yinghai Lu <yinghai@kernel.org>
To: Ravikiran G Thirumalai <kiran@scalex86.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>, Ingo Molnar <mingo@elte.hu>,
	torvalds@linux-foundation.org, linux-kernel@vger.kernel.org,
	shai@scalex86.org, Suresh Siddha <suresh.b.siddha@intel.com>
Subject: Re: [patch] x86: 2.6.31-rc7 crash due to buggy flat_phys_pkg_id
Date: Tue, 25 Aug 2009 12:36:23 -0700	[thread overview]
Message-ID: <4A943D37.4030604@kernel.org> (raw)
In-Reply-To: <20090825192757.GE6456@localdomain>

Ravikiran G Thirumalai wrote:
> On Tue, Aug 25, 2009 at 11:50:56AM -0700, Yinghai Lu wrote:
>> Cyrill Gorcunov wrote:
>>
>> initial apic id and apic id could be different.
>>
>> and we should use initial apic id to get correct phys pkg id in case BIOS set crazy apic id.
>>
> 
> Is there a specific bug we are fixing here?  Again, this behavior was
> present from atleast 2.6.15-2.6.30 on 'flat' and older 'cluster' apics, and intel
> documentation suggests local apic be used.  Is there a specific bios bug
> that is being fixed?
> 
> (The BIOS is not supposed to set a crazy apic ID.  The BIOS is buggy in that

we can not stop BIOS doing crazy thing.

for AMD 8 socket 4 cores system. BSP apic id : 4 or 8, and initial apic id is 0:

with apic id in phys_pkg_id, will get pkg id: 1, 2, ...

with initial apic id will get pkg id: 0, 1, 2, 3.

when I was working on LinuxBIOS, I did have one porting to have 
BSP: 0
AP: start from 5, 6, 7...
that will have strange in pkg_id.

YH