[Qemu-devel] Re: [Bochs-developers] [PATCH 5/6] Don't use unreserved memory inBIOS.

[Sebastian Herbszt]

Gleb Natapov wrote:
> On Fri, Oct 31, 2008 at 12:12:00AM +0100, Sebastian Herbszt wrote:
> > Gleb Natapov wrote:
> > > diff --git a/bios/rombios.h b/bios/rombios.h
> > > index f0ed88e..57b0f46 100644
> > > --- a/bios/rombios.h
> > > +++ b/bios/rombios.h
> > > @@ -56,7 +56,7 @@
> > > #define ACPI_DATA_SIZE    0x00010000L
> > > #define PM_IO_BASE        0xb000
> > > #define SMB_IO_BASE       0xb100
> > > -#define CPU_COUNT_ADDR    0xf000
> > > +#define CPU_COUNT_ADDR    0x0500
> >
> > Why did you pick 0x500?
> Cool number, don't you think so? It is unused location in a first page.
> if 0x666 is unused we can use it instead.

Actually 0050h:0000h seems to be used for PRINT-SCREEN STATUS.
This byte is used by the int 5h service, which is currently not
implemented. The EBDA could be used here or some reserved BDA
space (e.g. 0x4d0, 0x4ac).

- Sebastian