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

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?
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.


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