Re: [Qemu-devel] Call for testing QEMU aarch64-linux-user emulation

[Janne Grunau]

On 2014-03-06 11:40:47 +0000, Alex Bennée wrote:
> 
> Janne Grunau <address@hidden> writes:
> 
> > On 2014-02-25 15:54:37 +0000, Alex Bennée wrote:
> >>
> <snip>
> >> Have you got the log file "unsupported" line? I seem to recall you did
> >> ping me but maybe it was just on IRC? I just want to make sure I
> >> do the right ones. I'm working on this now.
> >
> > We spoke on irc about it. a quick test commenting unsupported
> > instructions out revealed that rshrn/2, sqrshrun and shrn/2 are
> > the only NEON instructions used in libav still missing support
> > in qemu master. Unsoppurted lines from qemu master 0459650d94d1
> > below.
> >
> > target-arm/translate-a64.c:6884: unsupported instruction encoding 
> > 0x0f0a8e10 at pc=00000000008632c8
> > target-arm/translate-a64.c:6884: unsupported instruction encoding 
> > 0x2f0b8f9c at pc=0000000000865764
> > target-arm/translate-a64.c:6884: unsupported instruction encoding 
> > 0x0f0a8610 at pc=0000000000863afc
> 
> I've just pushed support for the various shrn opcodes to:
> 
> https://github.com/stsquad/qemu/tree/ajb-a64-working

Thanks, just testing it and it seems to work as expected.

> I suspect if libav uses them heavily there could be some optimisation
> to be made as the narrow operations make heavy use of helpers to do the
> saturation stuff.

The saturating shift is not that heavily used and I don't care much as
long as qemu is an order of magnitude faster than ARM's foundation model
and much easier to handle than Apple hardware.

Janne