[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] Bug report about x86 'bt' insn
From: |
Torbjorn Granlund |
Subject: |
Re: [Qemu-devel] Bug report about x86 'bt' insn |
Date: |
Wed, 10 Nov 2010 15:15:43 +0100 |
User-agent: |
Gnus/5.11 (Gnus v5.11) Emacs/22.3 (berkeley-unix) |
malc <address@hidden> writes:
And this one was March 2009 (conveniently having the same file name
253666), the September 2010 issue reads differently:
Flags Affected
The CF flag contains the value of the selected bit. The ZF flag is
unaffected. The OF, SF, AF, and PF flags are undefined.
Have the qemu developers come to any decision on this one?
I haven't tested many 32-bit x86 implementations, but I think I have
tested all 64-bit x86 implementations, and they all seem to leave ZF
unaffected. (Clearly, it is possible that they do write it for some
values of the operands; there are too many possible values to test.)
I actually think qemu for both x86-32 and x86-64 should be changed to
make the bt insn not affect ZF. Considering that Intel have changed
their manuals (I have confirmed this) to say that ZF is unaffected,
there are even stronger reasons to change qemu. Even without that
documentation change, I would argue that compatibility with all defacto
hardware is important.
(I am not trying to say that my bug report was correct. It wasn't. I
have fixed the GMP code.)
--
Torbjörn
- [Qemu-devel] Bug report about x86 'bt' insn, Torbjorn Granlund, 2010/11/06
- Re: [Qemu-devel] Bug report about x86 'bt' insn, malc, 2010/11/06
- Re: [Qemu-devel] Bug report about x86 'bt' insn, Torbjorn Granlund, 2010/11/06
- Re: [Qemu-devel] Bug report about x86 'bt' insn, malc, 2010/11/06
- Re: [Qemu-devel] Bug report about x86 'bt' insn, Nathan Froyd, 2010/11/06
- Re: [Qemu-devel] Bug report about x86 'bt' insn, malc, 2010/11/06
- Re: [Qemu-devel] Bug report about x86 'bt' insn, malc, 2010/11/06
- Re: [Qemu-devel] Bug report about x86 'bt' insn,
Torbjorn Granlund <=
- Re: [Qemu-devel] Bug report about x86 'bt' insn, malc, 2010/11/10
- Re: [Qemu-devel] Bug report about x86 'bt' insn, Torbjorn Granlund, 2010/11/10
- Re: [Qemu-devel] Bug report about x86 'bt' insn, malc, 2010/11/10
- Re: [Qemu-devel] Bug report about x86 'bt' insn, malc, 2010/11/10