V2 issue

Stefan Reinauer stepan at suse.de
Mon Sep 29 15:01:01 CEST 2003


* ron minnich <rminnich at lanl.gov> [030929 21:08]:
> > Ron, Eric, can you confirm that your MPTable is correct for the Arima
> > Hdama? 
> 
> yes, I have booted SMP on the HDAMA using the SMP table from sourceforge. 
> Works fine. 
 
But you have no devices on bus 1, right? Are the devices on the other
busses there?

> > Looking into /usr/src/linux/arch/x86_64/kernel/pci-pc.c at function 
> > pci_scan_mptable():
> > 
> > If there is an MP Table, and it does not contain the bus, it will not be
> > scanned. Besides that it looks like setting pci=lastbus=<val> makes
> > Linux scan all the busses up to bus <val>.
> 
> well, that's a bad development. But at least you have solved the mystery, 
> almost. 
 
Linux tries to rely on the information firmware provides. Not that this
is always a good thing, but there are chipsets where free probing of the
bus just hangs the machine hard (I know that happens at least on the
X-Box) So having a careful default probably makes sense from an OS
perspective. The decision whether to trust hardware vendors or firmware
vendors is just a matter of taste I bet :) And of the fact that Firmware
can be fixed with a recompile ;-)

> Why do my bus 1 tg3s' work in SMP and not non-SMP if my mptable doesn't 
> have bus 1?

They work means that they work under Linux, or with etherboot? I suspect
that the interrupt routing is somewhat different on SMP and non-smp as
well but thats just a wild guess. Looking at AMD64's pci-irq.c I could
start wondering why it contains entries for the Intel PIIX and the Via
82C586 IRQ routers but not for the 8111 ;) But hey, there's a lot of
flexibility in that highlevel kind of programming 

  Stefan
-- 
Architecture Team
    SuSE Linux AG



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