linux-kernel - Re: [PATCH 1/2] VMware detection support for x86 and x86-64

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Message-ID: <20080916133239.GA17456@yantp.cn.ibm.com>
Date:	Tue, 16 Sep 2008 21:32:40 +0800
From:	Yan Li <elliot.li.tech@...il.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Yan Li <elliot.li.tech@...il.com>, Ingo Molnar <mingo@...e.hu>,
	linux-kernel@...r.kernel.org, joerg.roedel@....com,
	rjmaomao@...il.com, Yinghai Lu <yhlu.kernel@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>, nancydreaming@...il.com
Subject: Re: [PATCH 1/2] VMware detection support for x86 and x86-64

On Mon, Sep 08, 2008 at 05:34:07PM -0700, H. Peter Anvin wrote:
>> VMware may change the PCI ID at their will so I prefer checking the
>> DMI since it's easier.
>>
>> So if we ditched the official method we run the risk of some false
>> negatives.  But checking the DMI manufacturer would be good enough.
>>
>
> If we get false negatives that is quite frankly their problem, not ours.  
>  If nothing else, we should be able to look for a host bridge with the  
> VMWare vendor ID -- that should arguably be safer than DMI.

I found that in this situation we can't use PCI info.  My intention to
do this is to fix the false warning from
arch/x86/kernel/cpu/mtrr/main.c (around L695). When booting a VMware
guest we got:
"WARNING: strange, CPU MTRRs all blank?"

For VMware guest this warning is false, just as that for a KVM guest.

This code is from mtrr_trim_uncached_memory(), and used by
setup_arch(), which is used far before PCI is ready.

Therefore I think we can only use DMI here. Any idea?

Thanks!

-- 
Li, Yan

"Everything that is really great and inspiring is created by the
individual who can labor in freedom."
              - Albert Einstein, in Out of My Later Years (1950)
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