[Qemu-devel] Re: [PATCH][SEABIOS] Make SMBIOS table pass MS SVVP test

[Gleb Natapov <gleb@redhat.com>]

On Wed, Nov 25, 2009 at 09:09:19PM +0100, Sebastian Herbszt wrote:
> Gleb Natapov wrote:
> >On Tue, Nov 24, 2009 at 10:57:02AM -0500, Kevin O'Connor wrote:
> >>
> >>That said, I think SeaBIOS should autodetect any values where that's
> >>feasible.  So, for example, if the cpu identification is available via
> >>cpuid, then I think that should be used.  However, for example, if cpu
> >>model isn't available anywhere, then I think hardcoding something is
> >>okay.
> >It is used already where appropriate. To fill processor_id field in type
> >4 table. CPU manufacturer is different issue. CPU a guest is running on is
> >not manufactured by Intel or AMD, it is emulated by QEMU.
> 
> I am still wondering why you're against using the vendor reported by CPUID.
I am still wondering why you want this :) But let me ask you a question:
You are running some program inside QEMU and you encounter a bug. Some
instruction does not update eflags like it should and program fails. Do
you complain to
a) AMD
b) Intel
c) QEMU mailing list.

If your answer is (c), then I don't see how you can propose to put
something else then QEMU in manufacturer field.

> The cross vendor host cpu migration doesn't seem to be a sound reason, because
> the cpu in the guest is emulated and has no relationship to the host cpu.
> If i specify "-cpu phenom", i end up with an AMD cpu. Since noone but AMD
> produces this cpu it seems only reasonable to advertise the vendor as AMD.
> 
> >>> > >>>>>>>-    p->max_speed = 0; /* unknown */
> >>> > >>>>>>>-    p->current_speed = 0; /* unknown */
> >>> > >>>>>>>+    p->max_speed = 2000;
> >>> > >>>>>>>+    p->current_speed = 2000;
> >>
> >>SeaBIOS detects the current Mhz - see calibrate_tsc() in src/clock.c.
> >>
> >How accurate is it? What if I boot 100 guests on 16 cpu host
> >simultaneously? Not uncommon scenario. Those field really have no
> >meaning in virtualization environment. I'd rather have predictable
> >values there from boot to boot. Who know what Windows may use them for.
> 
> Speaking of not knowing what an OS or application might do with values in the
> SMBIOS table. Doesn't the same argument apply to the cpu vendor?
> 
I am concern with SMBIOS table be different on each boot, not what
information is stored in those fields. CPU manufacturer is free form
string. I have computers that have "Intel" there, others have "Intel(R)
Corporation". As long as it consistent from boot to boot it is OK IMO.

--
			Gleb.