Re: revert commit e4fd0475 ("hvmloader: always include HPET table")

[Paolo Bonzini <pbonzini@redhat.com>]

Il 03/07/2013 13:43, Jan Beulich ha scritto:
> Windows SVVP tests requiring a HPET ACPI table is in my opinion
> not a valid reason to always expose that table - respective tests
> should be run with "hpet=1" in the guest config file.
> 
> The problem here is that at least with qemu-traditional, which
> by default doesn't appear to emulate a HPET,

Isn't the HPET emulated in the hypervisor anyway?

> the advertising
> here can mislead an OS to believe that there actually is a usable
> HPET, which isn't true when neither Xen nor qemu emulate one.
> This ie being observed in reality: SLES9, being 2.6.5 based,
> doesn't have enough checking to notice that the HPET doesn't
> actually work.

Fair enough, the oldest I tested at the time was 2.6.9.

Paolo

> In fact, we may want to have an inverse mode (like a lot of
> hardware used to behave earlier on): A functional HPET that
> isn't exposed in ACPI tables, but that an OS knowing enough
> about the chipset can nevertheless find and use.