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

[Gleb Natapov]

On Mon, Nov 03, 2008 at 12:44:26AM +0100, Sebastian Herbszt wrote:
> 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).
>
The memory location can be reused after smp initialization.

--
                        Gleb.