Re: [Qemu-devel] [Bug 904308] [NEW] x86: BT/BTS/BTR/BTC: ZF flag is unaffected

[malc]

On Wed, 14 Dec 2011, Avi Kivity wrote:

> On 12/14/2011 06:22 PM, malc wrote:
> > On Wed, 14 Dec 2011, Avi Kivity wrote:
> >
> > > On 12/14/2011 06:08 PM, malc wrote:
> > > > On Wed, 14 Dec 2011, Daniil Troshkov wrote:
> > > >
> > > > > Public bug reported:
> > > > > 
> > > > > Hello!
> > > > > 
> > > > > Bug was found in qemu.git.
> > > > > See target-i386/translate.c:
> > > > > 
> > > >
> > > > [..snip..]
> > > >
> > > > Intel's documentation doesn't cover this, AMD's says that ZF is 
> > > > undefined, so,
> > > > question is: why do you think QEMU is wrong here?
> > > 
> > > The Intel documentation states that ZF is unaffected.
> > > 
> >
> > Right, i was blind, anyways, AMD disagrees. 
> >
> 
> Best to be conservative here.
> 

Point being, any code that relies on it being in any particular state is
broken (potentially, on AMD chips)

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