[SeaBIOS] [edk2] (PAM stuff) reset doesn't work on OVMF + SeaBIOS CSM
H. Peter Anvin
hpa at zytor.com
Thu Feb 14 21:54:20 CET 2013
On 02/14/2013 12:41 PM, Laszlo Ersek wrote:
>
> ). cpu_reset() [target-i386/helper.c] sets CS:IP to f000:fff0, which is
> the exact address of... reset_vector() in SeaBIOS.
>
This would be a bug, but it isn't quite true.
If you look at x86_cpu_reset() you will note that it sets the code
segment base to 0xffff0000, not 0xf0000 as one could expect from the
above. This is also true of a physical x86.
As such, the *real* reset vector is at 0xfffffff0 as opposed to the
SeaBIOS vector at 0xffff0 -- this is a backwards compatibility vector
which typically just issues a real reset.
Now, if Qemu doesn't handle the distinction here correctly, that is a bug.
-hpa
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