Re: APIC usb MPS 1.4 and the 2.4.2 kernel

[Pete Toscano <pete.lkml@toscano.org>]

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On Tue, 13 Mar 2001, Greg KH wrote:

> On Tue, Mar 13, 2001 at 12:25:13AM -0500, Pete Toscano wrote:
> > Well, I can't speak for the consequences of noapic (I've wondered as
> > much myself), but I know that there's been a problem with SMP 2.4
> > kernels (even the 2.4 test kernels) and USB running on VIA chipsets for
> > a while now.  I'm told by the linux-usb maintainers that it's a problem
> > with the PCI IRQ routing for the VIA chipsets, but I've been unable to
> > get anyone who knows about this to do anything (and I've been asking for
> > a while).  Alas, since this stuff is beyond me, I just accept the fact
> > that it'll probably always be broke.

> It seems that the APIC on this motherboard does not have most of the
> pins connected, so that even if we could get the USB interrupt to work
> properly (which we couldn't) there would be no benefit to run in APIC
> mode.  I was going to run some crude benchmarks on the box with and
> without APIC mode just to get an sense if we are missing anything
> running in noapic mode, but I haven't gotten around to it yet.

Very interesting.  I had not heard about this.  Are there any SMP boards
with a VIA chipset that does work well with Linux and USB?  I have an
old P2B-DS that I had replace with this board as I needed more PCI
slots.  Heck, for that matter are there any SMP boards that work well
with Linux and USB that have six or more PCI slots?

> But, Linux does seem to run just fine with USB and SMP in the noapic
> mode, which is a lot better than Win2000 can say, as it doesn't even
> support the VIA USB chipset on this board at all :)

How would this express itself?  I recently upgraded from WinME to Win2k
and it all _seems_ to be working well.  Where would I look to verify
this?

Thanks for the info and the update.

pete

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