Re: [Qemu-devel] [edk2] (PAM stuff) reset doesn't work on OVMF + SeaBIOS CSM

[David Woodhouse]

On Tue, 2013-02-19 at 21:49 +0100, Paolo Bonzini wrote:
> > And in fact it probably shouldn't use the hard-coded 0xcf9 reset; it
> > should use the one indicated by the ACPI RESET_REG field (which *is*
> > 0xcf9... or should be).
> 
> We should implement this: http://mjg59.dreamwidth.org/3561.html

Matthew fails to distinguish between a hard reset and a soft reset. From
the CSM if we do find ourselves running at 0xffff0 (which should never
happen except under buggy KVM emulation anyway), we really do need to be
using the 0xcf9 reset (or the ACPI reset, which is going to point to the
same thing in general), and *not* the keyboard reset. And, of course, we
need it to work correctly and reset the PAM configuration (qv).

However, a single bash on the 0xcf9 register ought to suffice so the
ACPI/kbd/ACPI/kbd loop that Matthew describes is probably acceptable. As
long as it does the ACPI one *first*.

( It's also interesting that, as Laszlo observes, machines tend to set
the RESET_REG in the FADT *without* setting the enabled bit in the FADT
flags. Does Windows use it anyway? And is there are reason for *not*
setting the enabled bit, or is it just that all PC BIOSes are written by
crack-smoking hobos that they drag in off the street, and this is just
an artefact of the rule "anything they *can* get wrong and still boot
Windows, they *will* get wrong"? )


-- 
dwmw2

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