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

[David Woodhouse]

On Mon, 2013-02-18 at 17:37 -0500, Kevin O'Connor wrote:
> The ACPI v2 spec describes a "hard" reset register.  SeaBIOS could
> extract it from the FADT and then use it.  Of course, we'd probably
> want to update the QEMU ACPI tables to implement ACPI v2 then.

This sounded great until I actually came to implement it.

The PIIX reset at 0xcf9 requires *two* writes; one to set the reset type
and then a second write with bit 2 set to actually do the reset.

The ACPI RESET_REG definition only allows for *one* value to be written.

Is that because the PIIX will actually do a hard reset when you write
0x06 to it *anyway*, despite theoretically saying that you should write
0x02 first? Or is the ACPI definition of RESET_REG simply incapable of
being used on the PIIX?

-- 
dwmw2

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