Re: [Qemu-devel] IMUL eflags update

[Johan Rydberg]

On Mon, 1 Dec 2003, Fabrice Bellard wrote:

: The solution used by Bochs to fix the problem is to say that imul
: modifies only OF and CF. The other flas are not modified.
:
: QEMU currently zeros all the other flags in order to have a faster flag
: update.
:
: By doing tests on a Pentium 4 processor, it seems that at least SF is
: set according to the result of the IMUL operation.
:
: So what is the best behavior to implement ? Bochs one or P4 one ?

The question is; do we want a working emulator, or a accurate emulator?

I rather see the latter, since adding workarounds for buggy software
will only endorce more buggy software.  People using QEMU for
developing operating systems might take for granted that the SF flag
will be modified by the mul/imul insns.

I could not care less [1] if Windows 3.11 can be booted in QEMU .

brgds
johan

 [1] From my point of view, supporting non-free software such as
     Microsoft products only promote them.  Instead we should
     promote free software.