Re: [PATCH 1/2] VMware detection support for x86 and x86-64

From: H. Peter Anvin
Date: Wed Sep 17 2008 - 11:39:42 EST


Ingo Molnar wrote:

that still leaves the CPUID/MSR method for the virtualizer to announce itself.


FWIW, it's getting pretty clear with the recent bout of Virtual PC bugs that we need virtualizer detection, and that a lot of VMs are doing various idiotic things.

Again, with Virtual PC, it seems that DMI is the preferred detection method, as disgusting as it is, simply because the alternatives are the moral equivalent of ad hoc probing for ISA cards (a random I/O port for VMWare, a random "hopefully unused" opcode for VPC.)

I feel It's also unfit to touch the whole PCI or DMI thing before CPU registers and memory are settled. A simple solution here is to only issue a KERN_INFO when we detected mtrr is empty and later, when we can be sure that the OS is not running as a VM, issue a warning. The later part can be done in early_quirks().

ok, we can move the MTRR message further back, to after the early quirks phase.

Makes sense to me.

-hpa

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