Re: [Qemu-devel] [PATCH] qemu: x86: report lapic version as 0x14 instead of 0x11

[Alexander Graf <agraf@suse.de>]

> Am 01.03.2014 um 03:14 schrieb "Gabriel L. Somlo" <gsomlo@gmail.com>:
> 
> Some guests (e.g. 0S X) insist on a minimum lapic version of 0x14.
> This patch bumps the emulated lapic version to 0x14 to accomodate that.
> 
> Signed-off-by: Gabriel L. Somlo <somlo@cmu.edu>
> ---
> 
> Along with the TCG ioapic polarity fix, this allows me to boot OS X
> without KVM acceleration.
> 
> I dug around the Intel docs and searched the Web, and there was nothing
> there to indicate any difference in functionality between lapic versions
> 0x11 and 0x14. It appears to me that lapic version is loosely correlated
> with the "generation" of the CPU it's attached to, and Apple simply decided
> to include an extra check that basically says "we don't support CPUs older
> than <foo>", where the oldest <foo> they support ships with lapics that
> were versioned to 0x14 :) For example:
> 
> http://www.opensource.apple.com/source/xnu/xnu-1456.1.26/osfmk/i386/lapic.c
> 
> Let me know what you think.
> 
> Thanks,
>  Gabriel
> 
> hw/intc/apic.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/intc/apic.c b/hw/intc/apic.c
> index 361ae90..67365b7 100644
> --- a/hw/intc/apic.c
> +++ b/hw/intc/apic.c
> @@ -675,7 +675,7 @@ static uint32_t apic_mem_readl(void *opaque, hwaddr addr)
>         val = s->id << 24;
>         break;
>     case 0x03: /* version */
> -        val = 0x11 | ((APIC_LVT_NB - 1) << 16); /* version 0x11 */
> +        val = 0x14 | ((APIC_LVT_NB - 1) << 16); /* version 0x14 */

Deja vu :). Should we really set this to thd least compatible version or rather to a current one that resembles roughly what we support? Otherwise patches like this will come up for every new osx release.

What is the version in Haswell?

Alex

>         break;
>     case 0x08:
>         apic_sync_vapic(s, SYNC_FROM_VAPIC);
> -- 
> 1.8.1.4
>