Re: [Qemu-devel] Intel 440bx hardware emulation correctness

[Jordan Justen <jljusten@gmail.com>]

Cristi,

My impression is that QEMU does not focus on strict hardware
emulation.  I think it would be counter-productive to (what I see as)
QEMU's main goals ... to emulate a functional system with good
performance.

It seems that the level of hardware compatibility is driven by
software dependencies.  Essentially, if an OS driver expects the
hardware to behave a certain way, then QEMU will emulate it to achieve
compatibility.

But, since the OS's do not generally know about SPD & configuring the
chipset memory, it is easier to ignore this completely in QEMU.

-Jordan

On Sun, Jul 26, 2009 at 9:37 AM, Cristi
Magherusan<Cristi.Magherusan@net.utcluj.ro> wrote:
> On Sun, 2009-07-26 at 14:35 +0300, Cristi Magherusan wrote:
>> Hello,
>>
>>
>> Does qemu aim to completely emulate the Intel 440bx northbridge hardware
>> (and maybe other) to detail, or instead does it on purpose skip some
>> parts for the sake of simplicity?
>>
>> As an example, I've seen that the RAM parameters are written in CMOS
>> instead of doing it using SPD and some RAM control registers, as
>> documented in the 440 datasheet.
>>
>> This only affects the BIOS code that does RAM detection, so the Bochs
>> BIOS code would also need to be changed accordingly.
>
> Actually, in fact I'm interested to find out wether there are other
> differences between qemu and a real 440bx-based motherboard, besides RAM
> detection.
>
> I'm asking because I'm willing to rewrite the coreboot qemu support code
> based on the generic northbridge/southbridge code.
>
> Thanks,
> Cristi
>
> --
> Ing. Cristi Măgherușan, System/Network Engineer
> Technical University of Cluj-Napoca, Romania
> http://cc.utcluj.ro  +40264 401247
>