Re: [Qemu-devel] Re: [PATCH 1/3] kvm-unit-tests: add x86 port io accessors

[Avi Kivity]

On 02/27/2011 04:01 PM, Anthony Liguori wrote:
> On 02/27/2011 06:44 AM, Avi Kivity wrote:
> > On 02/24/2011 11:48 PM, Anthony Liguori wrote:
> > > Signed-off-by: Anthony Liguori<address@hidden>
> > >
> > > diff --git a/lib/x86/io.h b/lib/x86/io.h
> > > new file mode 100644
> > > index 0000000..bd6341c
> > > --- /dev/null
> > > +++ b/lib/x86/io.h
> > > @@ -0,0 +1,40 @@
> > > +#ifndef IO_H
> > > +#define IO_H
> > > +
> > > +static inline unsigned char inb(unsigned short port)
> > > +{
> > > +    unsigned char value;
> > > +    asm volatile("inb %w1, %0" : "=a" (value) : "Nd" (port));
> > > +    return value;
> > > +}
> >
> > Are those %[wb] really needed?  gcc should do the right thing based 
> > on the argument type.
>
> It's just a little extra type safety.

Yeah, but those constraints aren't really documented.  Linux does use 
them in a handful of places so they're unlikely to go away though.

--
error compiling committee.c: too many arguments to function