Re: [Qemu-devel] [PATCH] PPC: Use correct values for 970 interrupts and hreset

[Blue Swirl]

On 2/28/09, Alexander Graf <address@hidden> wrote:
> The 970 doesn't set exception prefix values by default. According to
>  the ISA it just jumps to real mode with nip=vector.
>
>  Because of that the current hreset_vector is rendered invalid. Before,
>  it would go to excp_prefix (ROM base) + 0x100 (reset vector) and get
>  into the firmware.
>
>  But with the corrected excp_prefix, we now have to jump to the real
>  entry point, which is at 0xFFFFFFFC.

I don't think this is correct. 970FX uses HIOR to specify the
exception vector base, please see "IBM PowerPC 970FX RISC
Microprocessor", page 273.

>From OpenBIOS viewpoint both vectors are OK.

>  I can't imagine how any OS that does memory management itself could have
>  possibly worked with the code as it was.

Maybe Qemu uses the 604 exception prefix somewhere.