RE: [Xen-users] hvm, handle_mmio: failed to get instruction length

["Petersson, Mats" <Mats.Petersson@xxxxxxx>]

> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Tom Brown
> Sent: 17 August 2006 09:01
> To: xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-users] hvm, handle_mmio: failed to get 
> instruction length
> 
> 
> Is there a problem booting 2.4 kernels compiled on Redhat 7 machines? 
> After some sweat and cursing I've gotten a config where grub works 
> reliably, and I can get a 2.6 kernel to boot before it spills 
> its guts all 
> over, but I can not get an old 2.4 kernel to boot ... I 
> should dig out a 
> 2.2 kernel, as that actually would have a purpose, but I was 
> under the 
> belief (possibly/probably self delusion) that running linux 
> kernels with 
> HVM would be easy...
> 
> I've tried xen-3.0.2-2 and -unstable and now -testing... all 
> with the same 
> result. With unstable I did find a patch for can not find an 
> E820 memory 
> map... but I have not been able to find a fix for this one...
> 
> (XEN) Code bytes around(len=256) c01fc909:
> (XEN) c01fc900:0f 0d 86 40 01 00 00 0f 6f 06 0f 6f 4e 08 0f 6f 

I bet your kernel is compiled for "K7" or some such, right? It looks
like you're trying to perform a 3DNow!/MMX/SSE instruction, and that is
known to not work... 

Try building/using a 2.4 kernel compiled for "plain" i686 with no fancy
features. [It's faster anyways, since it will use the REP; MOVS
instruction to copy memory, which will intercept ONCE, and do all the
work inside Xen, then return, rather than multiple intercepts - as
opposed on real hardware were each read/write operation is the critical
path and getting more data into one write is helpful]. 

Appologies if my decoding of instructions is wrong, and you're actually
running a plain i686/i386 kernel - in that case, please reply again, and
I'll dig out the opcode list and try to figure out what goes on. 

By the way, it's entirely my fault that this doesn't work - I was
supposed to fix it, and I took a week's holiday when I should have been
working on it - hence I couldn't get a patch ready for the end of June -
July 1st I was put on a different project. My sincere appologies... 

--
Mats

> (XEN) c01fc910:56 10 0f 6f 5e 18 0f 7f 03 0f 7f 4b 08 0f 7f 53 
> (XEN) c01fc920:10 0f 7f 5b 18 0f 6f 46 20 0f 6f 4e 28 0f 6f 56 
> (XEN) c01fc930:30 0f 6f 5e 38 0f 7f 43 20 0f 7f 4b 28 0f 7f 53 
> (XEN) c01fc940:30 0f 7f 5b 38 4f 83 c6 40 83 c3 40 83 ff 05 7f 
> (XEN) c01fc950:af eb 45 0f 6f 06 0f 6f 4e 08 0f 6f 56 10 0f 6f 
> (XEN) c01fc960:5e 18 0f 7f 03 0f 7f 4b 08 0f 7f 53 10 0f 7f 5b 
> (XEN) c01fc970:18 0f 6f 46 20 0f 6f 4e 28 0f 6f 56 30 0f 6f 5e 
> (XEN) c01fc980:38 0f 7f 43 20 0f 7f 4b 28 0f 7f 53 30 0f 7f 5b 
> (XEN) c01fc990:38 4f 83 c6 40 83 c3 40 85 ff 7f b7 89 e8 83 e0 
> (XEN) c01fc9a0:3f 89 c1 c1 e9 02 89 df f3 a5 a8 02 74 02 66 a5 
> (XEN) c01fc9b0:a8 01 74 01 a4 0f 20 c0 83 c8 08 0f 22 c0 8b 04 
> (XEN) c01fc9c0:24 5a 5b 5e 5f 5d c3 89 f6 8d bc 27 00 00 00 00 
> (XEN) c01fc9d0:53 8b 5c 24 08 e8 d6 f6 f0 ff 0f ef c0 b8 3f 00 
> (XEN) c01fc9e0:00 00 8d b4 26 00 00 00 00 8d bc 27 00 00 00 00 
> (XEN) c01fc9f0:0f e7 03 0f e7 43 08 0f e7 43 10 0f e7 43 18 0f 
> (XEN) handle_mmio: failed to get instruction length
> (XEN) domain_crash_sync called from platform.c:846
> (XEN) Domain 12 (vcpu#0) crashed on cpu#1:
> 
> 
> any thoughts? AFAIK, there is nothing magic here. I can post 
> configs if 
> needed, but the dump seems like it is supposed to be 
> sufficient. No, I 
> have not compared all the hex dumps to see if they are 
> consistent... hhmm, 
> that probably is a good idea... yes, it looks quite repeatable.
> 
> -Tom
> 
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