| To: | Jan Beulich <jbeulich@xxxxxxxxxx> |
|---|---|
| Subject: | Re: [Xen-devel] [PATCH] vmx: last branch recording MSR emulation |
| From: | Keir Fraser <keir@xxxxxxxxxxxxx> |
| Date: | 2007年8月09日 14:20:23 +0100 |
| Cc: | Xin B Li <xin.b.li@xxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx |
| Delivery-date: | 2007年8月09日 06:18:13 -0700 |
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| Thread-topic: | [Xen-devel] [PATCH] vmx: last branch recording MSR emulation |
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On 9/8/07 14:05, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote: > The default of reading native registers is of course very questionable, but > it's been that way for so long that I didn't dare to kill this, as I'm > suspecting > that booting some, if not all, OSes without this would not work. And the then > likely resulting incrementally adding of emulation for individual MSRs on an > empirical basis is something that I consider, as pointed out on other similar > occasions like the MMIO instruction decoder, very wrong for code that is no > longer in a proof-of-concept state. Doing it the current way you get bitten when host MSRs contain unexpected values. This is why the MCE/MCA MSR handling got added -- some guests were getting confused, and thius crashing, on one particular host type that we hadn't tested on before. We're just storing up trouble for the future. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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