Re: [Qemu-devel] [PATCH 1/16] ARM Add ARM 920T identifiers

[Laurent Desnogues <laurent.desnogues@gmail.com>]

On Tue, May 26, 2009 at 1:29 PM, Jamie Lokier <jamie@shareable.org> wrote:
> Laurent Desnogues wrote:
[...]
>> It shouldn't.  I was thinking about how most people are misusing their
>> toolchain and think that if QEMU runs correctly some code, it should
>> run on the target.  In that particular case, that will fail :-)  For instance
>> LDM with PC used as procedure return does not behave the same
>> in v4T and v5 IIRC.
>
> I agree.  Especially for testing toolchains and architecture-specific
> code, it would be quite nice :-)
>
> I gather the x86 target is similarly lax with checking some things
> that a real x86 checks.

The existing ARM target is lax too, but quite close.  The main problem
is that the ARM architecture defines what is IMPLEMENTATION
DEFINED and also contains many UNPREDICTABLE behaviors, and
there are programs that rely on both, which basically means that if
one wanted an accurate simulation of all that, the ARM target would
be even more unreadable than it is now :)  Anyway architectural
compliance would be enough and I think it's highly desirable.


Laurent