Re: [Qemu-devel] RFC: fix run of 32 bits Linux executables on 64 bits targets

[Blue Swirl]

On 10/10/07, Fabrice Bellard <address@hidden> wrote:
> Thiemo Seufer wrote:
> > Fabrice Bellard wrote:
> >> J. Mayer wrote:
> >>> Following the patches done for elfload32, it appeared to me that there
> >>> were still problems that would prevent 32 bits executables to run on 64
> >>> bits target in linux user mode emulation.
> >>> [...]
> >> Are you sure it is a good idea to try to add 32 bit executable support to a
> >> 64 bit target ? In the end you will need to write a 64 bit to 32 bit linux
> >> syscall converter which would mean duplicating all the linux-user code of
> >> the corresponding 32 bit target (think of ioctls with strutures, signals
> >> frames, etc...).
> >
> > I would think this feature will be limited to platforms which can handle
> > 32bit and 64bit binaries with a single personality.
>
> I am not sure it is a common case !
>
> However, I suggest to emulate a 32 bit user linux system with a 64 bit
> guest CPU running in 32 bit compatibily mode. It would be useful to test
> 64 bit CPUs in 32 bit compatibility mode. The only required modification
> in linux user is to rename target_ulong so that it can have a different
> size of the CPU word default size.

I think this would be sufficient for the Sparc and this way there
would be no need to convert the structures. Brilliant!

Should we revert the elfload32 patch? What about PPC?