On Fri 2006-06-23 09:04:14, Dave Jones wrote:
> On Fri, Jun 23, 2006 at 02:46:56PM +0200, Pavel Machek wrote:
>
> > > > > --- linux-2617-pv.orig/arch/i386/kernel/cpu/cpufreq/powernow-k8.c
> > > > > +++ linux-2617-pv/arch/i386/kernel/cpu/cpufreq/powernow-k8.c
> > > > > @@ -1008,7 +1008,7 @@ static int __cpuinit powernowk8_cpu_init
> > > > > * an UP version, and is deprecated by AMD.
> > > > > */
> > > > >
> > > > > - if ((num_online_cpus() != 1) || (num_possible_cpus() != 1)) {
> > > > > + if ((num_online_cpus() != 1)) {
> > > > > printk(KERN_ERR PFX "MP systems not supported by PSB BIOS structure\n");
> > > > > kfree(data);
> > > > > return -ENODEV;
> > > > >
> > > >
> > > > Seems wrong to me... what if I boot, then hotplug second cpu?
> > >
> > > We only run this code if powernow_k8_cpu_init_acpi() has failed,
> > > which it should never do on an SMP system.
> > >
> > > So, you get exactly the same behaviour, as expected.
> > > You can't support >1 CPU with PSB.
> > >
> > > The above patch makes sure things continue to work if you run
> > > an SMP kernel on UP hardware.
> >
> > I'm pretty sure you'll find SMP machine with broken ACPI cpufreq
> > (therefore cpu_init_acpi() will fail).
>
> So? It fails now, it'll fail after this patch.
> That's not the situation that this patch is changing.
>
> If you have >1 CPU, you *must* have a working ACPI BIOS.
>
> > he might boot with one cpu then simulate hotplug of second one.
> >
> > 1) user is already doing perverse things at this point
> >
> > and
> >
> > 2) machine BIOS is b0rken
> >
> > ...so... it is only theoretical and probably not worth fixing.
>
> SMP kernel on UP hardware is not theoretical, and is worth fixing.
Problem _I_ pointed out is theoretical, so the patch is okay and sorry
for the noise.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
