Re: [Qemu-devel] [PATCH] multi-bytes nop and 64bits

[Mark Karpeles <mark@hell.ne.jp>]

Le mardi 21 avril 2009 à 21:20 +0400, malc a écrit :
> > Patch:
> > http://ookoo.org/svn/snip/qemu-0.10.1-nopl-fix.patch
> 
> I'm not intimately familiar with binutils' disasm but it looks correct
> save for the fact that hint_nop take M and not Ev as operand, which
> might be irrelevant for disassembler though...

To tell you the truth, I had a look at the current (ie. gdb 6.8) gdb
disassembler, and saw it was "Ev". It also produces correct result when
I look at the disassembled code (while the operand is irrelevant, it
gives a hint regarding the whole opcode's size).
I believe those who knows best how this decompiler works are those who
have continued to improve it, so I didn't look too deep in this, just
backported support for multibyte nop to code used in qemu (tried to port
the whole decompiler, but it changed too much, and I'm too lazy to
attempt to fix that).

I'm just adding [PATCH] to the subject, just to let everyone here know
this mail contains a patch. I successfully tested it on 3 machines
without problems and it already saved my day once by showing me where my
kernel was stopping (I'm in the process of porting from 32bits to
64bits, knowing what happens inside is a great help).

Anyway the decompiler obviously needs to be either re-made, or
re-imported from gdb, but this little patch will help until someone with
better knowledge of qemu and gdb does it.


Mark