On Sat, 2007-04-28 at 10:42 +0200, Andi Kleen wrote:
> On Saturday 28 April 2007 09:52:30 Jeremy Fitzhardinge wrote:
> > Eric W. Biederman wrote:
> > > Next time I'm in a really tormenting mood I will fire up my
> > > my ibm ps2 with it's 16Mhz 386 and 6MB and verify that all is working
> > > well there.
> > >
> >
> > Well, that would be interesting. From a subarch perspective, it would
> > just be the normal default, and in theory it should work fine. But I
> > suspect the fpu emulator is probably broken, and non-WP is likely to
> > have rotted,
>
> AFAIK it's been tested occasionally on some embedded 386 systems
> (e.g. by Thomas Gleixner). Probably not with the recent changes though.
>
> > and lots of other things. Is that an MCA machine?
>
> Yes should be.
>
> > > I really don't think it is ok to be cavalier about anything
> > > that we actually support. Usually if we can handle the general
> > > case it makes for better more maintainable code.
> > >
> > > So far the paravirt class of machines seems every bit as much a subarch
> > > as voyager and every bit as interesting.
> > >
> > Well, not really. The problem with the subarch mechanism is that it
> > promotes a lot of copied code with small modifications, and so making
> > changes is the inherently non-general activity of trying to find all the
> > various copies, work out what subtle differences they have, and try to
> > make the appropriate changes in each case. This was one of the major
> > objections to the original Xen-as-subarch patches, and it is the problem
> > with Voyager. The mass of preprocessor tricks doesn't help either.
>
> Yes I agree. Current i386 subarch is a mess and I hope to slowly phase
> it out. mach-{es7000,summit} should just be folded into mach-generic
> always (like x86-64) and I'm somewhat hoping that mach-voyager and
> perhaps mach-visws too will just go away at some point.
You wish ...
> The future direction are focussed pluggable interfaces like genapic, smp_ops etc.
Actually, pluggable smp_ops might make voyager look far more standard
(that's pretty much most of what the subarch code does for voyager).
Pluggable genapic would probably be at the wrong level ... voyager is
non-apic based SMP and doesn't fit well into the apic abstraction.
James
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