Re: [Qemu-devel] [PATCH] improve emulation correctness

[Michael Tokarev]

25.04.2014 21:24, Peter Maydell wrote:
> On 25 April 2014 09:13, Dmitry Poletaev <address@hidden> wrote:
> 
>> Emulated program can execute that test and after that
>> can understand environment not real.
> 
> It is always going to be possible to determine that you're
> running on an emulator rather than real hardware, so changing
> QEMU behaviour just for this is uninteresting. If QEMU
> behaves differently from the specification (in this case
> the x86 hardware and architecture manuals) that's an interesting
> bug. If we just happen to choose a different undefined
> behaviour from that which hardware does, that is not in
> my opinion a problem.

Actually it might be a problem.  We know a ton of examples where
hardware had bugs and software had to compensate and actually
_expect_ buggy behavour.  Or when software depends on (reliable
repeating) certain behavour in undocumented parts, and hell
breaks when this (undocumented!) behavour changes.

Thanks,

/mjt