[Xen-devel] RE: One question on mcinfo_extended

["Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>]

I think two issues here:
a) As said in previous mail, the mc_msrs is set to be 19, while for dom0, 
mcinfo_extended contains at most 16. So if dom0 code simply loop based on 
mc_msrs, it may be wrong.
b) 32-bit dom0 can't get the extended MSR (r8. r9 etc), which is still needed 
for analysis IMO.

One hack I can think out is, if dom0 is 32-on-64, we can change the mc_msrs 
when copy that to guest in XEN_MC_fetch, but that should not fix item b still.

In fact, I don't know if any platform has this extended MSR capability :(

--jyh

>-----Original Message-----
>From: Jan Beulich [mailto:jbeulich@xxxxxxxxxx]
>Sent: Tuesday, April 20, 2010 4:39 PM
>To: Jiang, Yunhong
>Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
>Subject: Re: One question on mcinfo_extended
>
>The point of using void* here is that even in a 32-bit Dom0 running on 64-bit 
>Xen
>should have access to all registers - I couldn't think of anything better back 
>then. The
>implication is that Dom0 side code must be prepared to deal with that - which 
>I think
>isn't the case at present.
>
>Jan
>
>>>> "Jiang, Yunhong"  04/20/10 10:20 AM >>>
>Hi, Jan, in 19465 changeset, the mcinfo_extended's mc_msr is changed to be an
>array of sizeof(void *) * 4. I assume your purpose is to make it works on both 
>32 and
>64. But will it cause trouble to compatibility mode dom0? Especially if dom0 
>copy the
>information to local variable, and loop the variable through
>mcinfo_extended->mc_msrs?
>
>Thanks
>--jyh


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