linux-kernel - Re: [PATCH] [3/4] x86: MCE: Improve mce_get

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Message-ID: <87eiw3a29h.fsf@basil.nowhere.org>
Date:	Wed, 08 Apr 2009 12:06:02 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
Cc:	ying.huang@...el.com, hpa@...or.com, linux-kernel@...r.kernel.org,
	mingo@...e.hu, tglx@...utronix.de
Subject: Re: [PATCH] [3/4] x86: MCE: Improve mce_get_rip

Hidetoshi Seto <seto.hidetoshi@...fujitsu.com> writes:

> Andi Kleen wrote:
>> From: Huang Ying <ying.huang@...el.com>
>> 
>> Return rip/cs if MCG_STATUS_EIPV is set in mce_get_rip(). Remain m->cs
>> if RIP is read from rip_msr.
>
> It means we use "Error IP" as "Return IP" if RIPV=0 but EIPV=1 ...?
> Sounds strange.

It's not return IP, but "reported IP" in this case.

> Why this "forcing EIPV=1" still required?
> I think remaining this line will make something wrong.

Yes it's wrong. I'm dropping this in a later patch.
BTW current CPUs don't support this MSR anyways, it was a P4 only feature.

>

> I guess it would make much sense if we stop mixing RIP and EIP and rename
> the mce_get_rip() to mce_get_eip(), and the rip_msr to eip_msr too.

Ok fair enough.  I admit the code was always a bit dubious.

> And then it would be acceptable if we print RIP with "!INEXACT!" annotation
> instead of printing precise EIP in case of RIPV=0 but EIPV=1.

Please send a patch to do all that.

-Andi
-- 
ak@...ux.intel.com -- Speaking for myself only.
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