Re: [Qemu-devel] [PATCH v2 1/6] Use IO port for qemu<->guest BIOS communication.

["Blue Swirl" <blauwirbel@gmail.com>]

On 9/7/08, Anthony Liguori <anthony@codemonkey.ws> wrote:
> Gleb Natapov wrote:
>
> > On Wed, Aug 27, 2008 at 08:10:49PM +0300, Blue Swirl wrote:
> >
> >
> > > On 8/27/08, Gleb Natapov <gleb@qumranet.com> wrote:
> > >
> > >
> > > >  On Tue, Aug 26, 2008 at 07:46:20PM +0300, Blue Swirl wrote:
> > > >  > > Is the patch below what you mean? (not tested, but compiles)
> > > >  >
> > > >  > Yes, but I'd still put the code from the .h file and pc.c to a new
> .c
> > > >  > file, only the keys and function prototypes to .h.
> > > >  >
> > > >
> > > > Okey, here is updated one (compiled only)
> > > >
> > > >
> > > I added some missing pieces like static/const keywords, device
> > > save/load and reset, MMIO and Sparc32/64 support. I also renamed some
> > > names for consistency.
> > >
> > >
> > Thanks! I'll rebase my other patches on this and will test it.
> >
> >
>
>  I think this is missing save/restore support.  What happens if you do a
> save, move to a different machine, then do a restore, and reboot?  The guest
> will see a different value IIUC.
>
>  Also, instead of returning 0 on non-linux systems, why not just return some
> fixed value?  It's no more "wrong" than returning the host clock rate.

You commented the wrong patch, but anyway: the clock rate will be
saved by configuration device. Loading will be done after hardware has
been initializers have been called, so the saved value will be used.

The rates may be incorrect anyway. If x86 CPU definitions one day
include i386, giving i386 a modern frequency in GHz range can surprise
some guests.

I think Fabrice didn't like to use floating point arithmetics inside
the emulator, but I can't find a reference.

Otherwise, a mechanism to present the CPU frequency would be useful,
maybe even to other targets.