Re: [Xen-devel] Xen 4.3 development update RC2 imminent

[George Dunlap <george.dunlap@xxxxxxxxxxxxx>]

On 23/05/13 11:39, Andrew Cooper wrote:
> On 23/05/13 11:36, Fabio Fantoni wrote:
> > Il 23/05/2013 09:39, Jan Beulich ha scritto:
> > > > > > On 22.05.13 at 18:54, George Dunlap <george.dunlap@xxxxxxxxxxxxx> wrote:
> > > > On 22/05/13 17:30, Pasi KÃrkkÃinen wrote:
> > > > > On Wed, May 22, 2013 at 04:05:27PM +0100, George Dunlap wrote:
> > > > > Hmm, for testing, can we use cpuid to mask out SSE,
> > > > > and then try qxl ?
> > > > That had occurred to me -- Andrew / Jan, do you know which flag might
> > > > disable this particular instruction?
> > > >
> > > > I guess we could try just disabling all the SSE instructions.
> > > movdqu is an SSE2 instruction, so disabling bit 26 of CPUID EDX
> > > output to EAX=1 input.
> > Can you explain better please?
> > Should I add this to test it?
> > cpuid="host,sse=0,sse2=0,ssse3=0,sse4_1=0,sse4_2=0,eax=1"
> It will likely not work.  SSE2 is an architectural requirement for 64bit.
>
> It means that 64bit code may assume the presence of SSE2.  Xen amongst
> other software does make this assumption.
It might work if he's using 32-bit.

Fabio, as I said in my initial e-mail, you need to:

1. Run "cat /proc/cpuinfo" on your dom0
2. Look at the line that says "features:"
3. Find all the things that contain "sse" > 2 (sse2, ssse3, &c)
4. Set them to 0 in the "cpuid" field like above.

Every processor will be a bit different -- you can't just copy mine and 
expect it to work.
Don't include "eax=1" -- Jan is thinking of a different interface.

 -George

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