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

    * Yan Li <elliot.li.tech@gmail.com> wrote:

    > On Wed, Sep 17, 2008 at 12:52:38PM +0200, Ingo Molnar wrote:
    > > > This code is from mtrr_trim_uncached_memory(), and used by
    > > > setup_arch(), which is used far before PCI is ready.
    > > >
    > > > Therefore I think we can only use DMI here. Any idea?
    > >
    > > PCI quirks can be used almost arbitrarily early stage, see:
    > > arch/x86/kernel/early-quirks.c.
    > >
    > > Adding a VM identification callback to early-quirks.c would be fine. But
    > > if there's a reliable and specific enough DMI string that's fine as
    > > well. (but PCI is better, since it's a generally more stable enumeration
    > > interface)
    >
    > The problem here is that mtrr_trim_uncached_memory() is called 108
    > lines before the invocation of early_quirks(), and 48 lines before
    > that of dmi_scan_machine(). That's quite early. The only thing ran
    > before that is the initialization of CPU, so we have nearly nothing to
    > use to check the fingerprint of the underlying machine.

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

    > 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.

    Ingo


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