From: Ingo Molnar
Date: Sun Jan 18 2009 - 02:14:54 EST

* Brian Gerst <brgerst@xxxxxxxxx> wrote:

> On Sun, Jan 18, 2009 at 12:59 AM, Tejun Heo <tj@xxxxxxxxxx> wrote:
> > Brian Gerst wrote:
> >> On Sun, Jan 18, 2009 at 12:05 AM, Tejun Heo <tj@xxxxxxxxxx> wrote:
> >>> Hello,
> >>>
> >>>> --- a/arch/x86/kernel/setup_percpu.c
> >>>> +++ b/arch/x86/kernel/setup_percpu.c
> >>>> @@ -147,6 +147,9 @@ unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
> >>>> #endif
> >>>> EXPORT_SYMBOL(__per_cpu_offset);
> >>>>
> >>>> +DEFINE_PER_CPU(int, cpu_number);
> >>>> +EXPORT_PER_CPU_SYMBOL(cpu_number);
> >>> This is inside CONFIG_HAVE_SETUP_PER_CPU_AREA. I think voyage would
> >>> be unhappy with this change.
> >>
> >> Is there any specific reason Voyager doesn't use the x86
> >> setup_per_cpu_areas() function? I don't see anything on a quick
> >> glance that would not work. The x86 code is pretty much a superset of
> >> the default code in init/main.c.
> >
> > I have no idea at all. Given that not many people can test it, I
> > figured just leaving it alone would be the best course but if it can
> > be merged, all the better.
> Unfortunately Voyager doesn't compile currently for unrelated reasons.
> I'll take a look at incorporating it into these patches, but I can't
> even do a compile test right now.

Peter/James, what's the current status of x86/Voyager cleanups?

A couple of months ago i made a few suggestions about how to convert
Voyager to the cleaner x86_quirks 'quirks HAL' (from the current fragile
and hard and expensive to maintain 'compile time HAL'), but it didnt seem
to go anywhere. See the discussion of this timeframe:


The VisWS subarch (which was a similarly excentric design that was only a
PC in terms of having Intel CPUs) has been converted to CONFIG_X86_VISWS
already, with arch/x86/kernel/visws_quirks.c holding the optional quirk

The desired end result would be to have a CONFIG_X86_VOYAGER=y build mode
that adds the quirk handlers to an otherwise generic kernel, with most of
the quirks concentrated into a single arch/x86/kernel/voyager_quirks.c
file - instead of having a full subarch for x86/Voyager. Both
arch/x86/mach-voyager/ and arch/x86/include/asm/mach-voyager/ would go
away in the end - because all functionality is merged into the generic
code and the quirks would be in voyager_quirks.c.

I'd be glad to lend a helping hand both with the patches and with testing
on non-Voyager - especially the SMP bits probably need extensions on the
x86_quirks side. (And i'm sure the other x86 maintainers would we glad to
help out with this process too.)

x86/Voyager is the last holdout in this area, and with an active kernel
developer like James behind it it ought to be fixable - should James have
the time/interest.

If there's no time/interest in that then we can temporarily mark Voyager
CONFIG_BROKEN until cleanup/fix patches arrive.

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