Re: 32-bit qemu + 64-bit kvm be a problem?

[Michael Tokarev <mjt@tls.msk.ru>]

02.06.2010 09:44, Neo Jia wrote:
> On Wed, Mar 10, 2010 at 2:12 PM, Michael Tokarev<mjt@tls.msk.ru>  wrote:
[]
>> I use 32bit kvm on 64bit kernel since the day one.  Nothing of interest
>> since that, everything just works.

> I just came back to this thread because I am seeing that I can't run
> VISTA 64-bit inside 64/32 mode, which will crash with bugcheck 0x5D.
> Is this a known issue?

I haven't seen it myself, but I never tried vista.  Win7 64bit installs
and works just fine.  STOP 0x0000005D, according to M$, means "there is
a processor present that is not supported".  I'd say try to experiment
with different -cpu options.  Also see if it works in native 64bit mode.

>> Recently (this week) I come across a situation when something does not
>> work in 64/32 mode.  Namely it is linux aio (see the other thread in
>> kvm@ a few days back) - but this is not due to kvm but due to other
>> kernel subsystem (in this case aio) which lacks proper compat handlers
>> in place.
>
> Could you tell me more about the AIO issue? Will this will slow down
> the guest if it does a lot I/O? Will setting up coalescing help?

You can search it yourself.  In a nutshell it's an optimisation in kvm
since version 0.12  to let raw devices be used a bit more efficient.

/mjt