Re: [Qemu-devel] 3 new x86 instructions

[Torbjorn Granlund]

Richard Henderson <address@hidden> writes:

  I've updated that branch; please try again.
  
Thanks.

I am no friend of git's, and my mercurial commands (pull -u) cause
million conflicts.

OK, I grabbed a new copy and have built it.  It works better, sshd now
runs.

Somethings seems wrong with adcx and/or adox.  Or I have completely
misundersand how they are supposed to work.  Or gdb (6.1.1) lies to me.
(Building a newer gdb now.)

The apparent symptom is that an

    adox (%rdi,%rcx,8), %r9

where the 8 bytes at the memory location contains just zeros,
and r9 is some random value, results in OF being set.

I trace this behaviour from gdb.  I have reasons to mistrust gdb, since
if I stick an "jo ." after the adox insn, it does not hang.

My attempts at creating trivial stand-alone test has failed.

I only have Intel's 327831.pdf document which does not accurately
document adcx or adox.  Their detailed manuals are aparently silent
about these insns.

Does qemu ever fold foldable constructs like

     move $0, %rax
     add  %rax, %rax

?

That could explian why my stand-alone tests cannot trigger the apparent
problem.

-- 
Torbjörn