Re: [Qemu-devel] [PATCH] ppc32 guests: fix computation of XER.{CA, OV} in addme, subfme, mullwo

[J. Mayer]

On Wed, 2008-06-18 at 00:06 +0200, Julian Seward wrote:
> On Tuesday 17 June 2008 14:27, Aurelien Jarno wrote:
> > On Sun, May 11, 2008 at 02:04:47AM +0200, Julian Seward wrote:
> > > For ppc32 guests, computation of XER.CA and XER.OV in some obscure
> > > cases is incorrect.  At least, it doesn't produce the same results
> > > as a real MPC7447, and doesn't appear to be in accordance with the
> > > instruction set documentation.
> > >
> > > The attached patch fixes it:
> > >
> > > * addme{o}{.}, subfme{o}{.}: compute XER.CA correctly
> > >
> > > * mullwo{.}: sign extend arguments before doing 64-bit
> > >   multiply, so as to make the XER.OV computation correct

which seems to already been done... (and tested many times)

> > Could you please give us a corner case for at least one of the
> > instructions? It would help to clearly understand the problem.
> 
> Below is a test case showing the problem with mullwo, addme and
> subfme.  On a real 7447 it prints

This patch looks really ugly, does not respect the coding style and
addme/subme changes seem very suspicious to me... I won't merge this
as-is, but I could check more on real hardware I got (from 601 to G5).

Could you please exactly describe the test conditions (host, ...) ?

Thanks

[...]

-- 
J. Mayer <address@hidden>
Never organized