New subject: Geode GX1 and IRQ tables

1 Mar 2005


      The URL for the Cox/Weinigel thread about PIRQ tables
on the geode gx1 is at:
http://lkml.org/lkml/2002/7/5/104
I'm doing a little bit more analysis of the problem
now. I've been looking at the following block of code
from 2.6.10's pci/irq.c. First of all, LB states this
during bootup:
---
Checking IRQ routing tables...
/bios/freebios/src/arch/i386/lib/pirq_routing.c:   
30:check_pirq_routing_table() - irq_routing_table
located at: 0x00008740
done.
Copying IRQ routing tables to 0xf0000...done.
Verifing priq routing tables copy at 0xf0000...failed
Wrote linuxbios table at: 00000500 - 00000664 
checksum f9fe
---
I'm not sure why the copy to 0xf0000 failed. That's
kinda odd but I'll live with it for now. Now, I put
some debug in the kernel code to see whether it found
the pirq table and I saw:
---
no pirq_table so calling pcibios_get_irq_routing_table
pirq_table=00000000
---
coming from pcibios_irq_init. So based on the code
appended below, I believe that the kernel isn't
finding the pirq table. And I think this is because
the kernel's pirq_find_routing_table function only
looks from __va(0xf0000) to __va(0x100000) whereas LB
puts it at 0000500. The second attempt that the kernel
makes to get the PIRQ table is with
pcibios_get_irq_routing_table and that fails too. I
need to look at that, but first I think I'll look into
why the copy to f0000 fails. In the meantime, any
advice?
---
static int __init pcibios_irq_init(void)
{
        DBG("PCI: IRQ init\n");
if (pcibios_enable_irq || raw_pci_ops == NULL)
                return 0;
dmi_check_system(pciirq_dmi_table);
pirq_table = pirq_find_routing_table();
#ifdef CONFIG_PCI_BIOS
        if (!pirq_table && (pci_probe &
PCI_BIOS_IRQ_SCAN)) {
                printk(KERN_WARNING "no pirq_table so
calling pcibios_get\n");
                pirq_table =
pcibios_get_irq_routing_table();
                printk(KERN_WARNING
"pirq_table=%p\n",pirq_table);
        }
#endif
        if (pirq_table) {
                printk(KERN_WARNING "had
pirq_table\n");
                pirq_peer_trick();
                pirq_find_router(&pirq_router);
                if (pirq_table->exclusive_irqs) {
                        int i;
                        for (i=0; i<16; i++)
                                if
(!(pirq_table->exclusive_irqs & (1 << i)))
pirq_penalty[i] += 100;
                }
                /* If we're using the I/O APIC, avoid
using the PCI IRQ routing table */
                if (io_apic_assign_pci_irqs) {
                        printk(KERN_WARNING "using
io_apic to assign irqs\n");
                        pirq_table = NULL;
                }
        }
pcibios_enable_irq = pirq_enable_irq;
pcibios_fixup_irqs();
        return 0;
}
---
--- "Ronald G. Minnich" rminnich@lanl.gov wrote:
...
On Tue, 1 Mar 2005, Richard Smith wrote:
...
I've found that Linux up to 2.6.9 (I haven't
tested .10)  Dosen't do
...
this fully.  With my 440bx chipset there are
config registers in the
...
northbridge that control which IRQ line each of
the PCI PIRQ lines are
...
routed to.  Even with a proper PIRQ table these
registers are not setup
...
and I get the same error reported.
that's whacky. The old linux did fine with 440bx. I
never had to do 
anything but set up PIRQ tables.
...
I suggest you diff the output of lspci -xxx for
the northbridge between
...
linubios and factory bios and resolve all the
differences with the
...
datasheet.
on the geode 2.4.18 always worked, and if I patched
linux for later 
linuxes, that worked fine too.
What a mess PIRQ got to be ....
ron
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Re: Geode GX1 and IRQ tables

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