x86: detect running on a HyperV system
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From: Hank Janssen on 7 May 2010 12:30 SNIP SNIP SNIP---------- > From: Greg KH [greg(a)kroah.com] - Friday, May 07, 2010 8:46 AM > >[KY added to the To:, sorry for not including him earlier, he wrote this >code] On Thu, May 06, 2010 at 06:49:31PM -0700, H. Peter Anvin wrote: >> On 05/06/2010 12:18 PM, Greg KH wrote: >> > On Thu, May 06, 2010 at 12:13:17PM -0700, H. Peter Anvin wrote: >> >> On 05/06/2010 12:08 PM, Greg KH wrote: >> Okay... we write something called x86_hyper_features, but it isn't >> actually used for anything. I'm assuming based on what I can see in >> <asm/hyperv.h> that it is almost certainly not anything CPU-based. I >> really don't like a random field that can be stuffed with information >> from random locations, and it doesn't look like it's even a flag field >> in any meaningful way. Worse, the field is just used to mix bits from >> two different CPUID levels at what appears to be a completely arbitrary >> boundary: >> >> /* >> * Extract the features, recommendations etc. >> * The first 9 bits will be used to track hypervisor features. >> * The next 6 bits will be used to track the hypervisor >> * recommendations. >> */ >> cpuid(HYPERV_CPUID_FEATURES, &eax, &ebx, &ecx, &edx); >> c->x86_hyper_features |= (eax & 0x1ff); >> >> cpuid(HYPERV_CPUID_ENLIGHTMENT_INFO, &eax, &ebx, &ecx, &edx); >> c->x86_hyper_features |= ((eax & 0x3f) << 9); >> >> Why 9? Why 6? The only thing that I can think of that justifies those >> particular numbers is what the *current* version of Hyper-V does. > >I think that is what Hyper-V is saying it will always do. Hank? Any >help here? That is correct. Hyper-V will always do this. For functionality like a timesource, we need to get to hyper-v the way Ky did in his code. There is no messaging for it like IDE/SCSI/Network and the like. My understanding is that more information is going to be contained in these areas once Windows 8 is more defined. I know Windows 8 will give us changes but we do not know yet what they are. And I will not untill much later in the year. They are designing some of the low level stuff there right now. I know that some of the messaging protocols will change regarding networking. Hank.-- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |