Re: [Xen-devel] [PATCH] Disable Xen PowerNow! support on Opteron 2nd gen and earlier processors

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 29/1/08 09:53, "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx> wrote:

> As promised I've instrumented and kicked that code path, and I execute it
> with no problems, with the VCPU concerned being correctly migrated before
> and after the continue_hypercall_on_cpu() is executed. I've tried it with
> 'dom0_vcpus_pin' and also I've tried making fairly extreme calls to
> cpu_frequency_change() inside the hypercall-continuation 'helper' function.
> None of this causes my dom0 boot to hang. So it looks like something a bit
> subtle must be going wrong on your test system.

Actually I've now eyeballed the problem. We access a stack variable after
the stack frame is gone away. Probably we therefore end up setting a CPU's
frequency to zero, which is not good at all. I'll work up a fix.

 -- Keir



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