Message-ID: <4FBD39BE.8040101@zytor.com>
Date: Wed, 23 May 2012 12:25:50 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Thomas Gleixner <tglx@linutronix.de>
CC: Avi Kivity <avi@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>,
        kvm@vger.kernel.org, Marcelo Tosatti <mtosatti@redhat.com>,
        Ingo Molnar <mingo@redhat.com>, x86@kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kvm: optimize ISR lookups
References: <20120521163727.GA13337@redhat.com> <alpine.LFD.2.02.1205211940030.3231@ionos> <4FBB7185.6040105@redhat.com> <alpine.LFD.2.02.1205221919260.3231@ionos> <4FBCFDD1.5050405@redhat.com> <alpine.LFD.2.02.1205232037220.3231@ionos>
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On 05/23/2012 11:37 AM, Thomas Gleixner wrote:
>>
>> That works, but replaces one problem with another: now we have two
>> sources for the same data, and need to juggle between them depending on
>> register number (either synchronizing in both directions, or special
>> casing); so you're simplifying one thing at the expense of the other.
>> If the microcode starts accessing more registers, then having two
>> layouts becomes even uglier.
> 
> Fair enough :)

Yes, the µcode accessing this data structure directly probably falls
under the category of a legitimate need to stick to the hardware format.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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