Re: [Qemu-devel] [PATCH v2 0/5] disas: add libvixl to support A64 disassembly

[Peter Maydell]

On 29 January 2014 20:01, Laurent Desnogues <address@hidden> wrote:
> On Tue, Jan 28, 2014 at 12:45 PM, Peter Maydell
> <address@hidden> wrote:
>> Ping for review/testing/comments on this version, please?
>
> I still dislike the idea of importing so much code in particular for
> something that is incomplete:  as far as I can see, AdvSIMD
> instructions are not supported.  The very least that should be
> done would be to add a file that gives a rough status of what is
> and what is not implemented.

I can add some text to a brief README file, sure.

> And what if the vixl authors never implement AdvSIMD?  This
> is the most difficult part of Aarch64 to disassemble (integer and
> FP instructions are really easy to disassemble).  Will someone
> add these and will vixl authors accept the changes or will we
> then start diverging from vixl implementation?  Is vixl even still
> supported or in development (no commit for 6 months)?

As I understand the situation, it is supported but the model
is more "we'll push out a release occasionally when we've
done a big chunk of work" rather than a continuously updated
public-facing git tree.

This is no worse at all (in fact better) than the situation we have
with the binutils disassemblers in the tree at the moment -- those
are effectively totally unmaintained by their upstream as
a result of the GPL2/GPL3 split.

I agree that it would be nice if we supported the SIMD
instructions in the disassembler. Adding them to vixl
should be no worse than adding them to anything else,
and I'd rather have a disassembler that supported at
least the integer set than none at all.

thanks
-- PMM