Re: [Qemu-devel] qemu-system-ppc problem with PVR access from user space

[Daniel Jacobowitz <drow@false.org>]

On Fri, Nov 02, 2007 at 05:23:59PM +0100, Jocelyn Mayer wrote:
> No, it's not accidental. An application accessing priviledged SPR,
> including the PVR, is likely to be buggy. I checked in the kernel
> (2.6.23), trapping the mfpvr instruction is a huge bug because it breaks
> the virtualisation features of the PowerPC architecture. Application
> like mol will suffer of this, not being able to pretend the virtualized
> CPU is not the same as the host CPU. The PowerPC architecture has been
> designed to be fully virtualisable but the vanilla Linux kernel breaks
> this useful feature. The bug is then to be fixed in the kernel (and the
> glibc if it really uses mfpvr).

I suggest you take this up with the PowerPC kernel maintainers, which
might work, instead of making QEMU noisy about it; the people using
QEMU don't care, and they'll just disable the warning.  It wasn't
an accidental decision on the kernel maintainers' part either.

I don't see the PVR read in current glibc, but I thought it was there;
I don't remember exactly what happened.

-- 
Daniel Jacobowitz
CodeSourcery