[Xen-devel] Problems with latest unstable 1.3

["Barry Silverman" <barry@xxxxxxxxx>]

I have been trying out the latest unstable with the new i/o and have found
the following issue. I created a xen.gz with nodev=y set, and tried it out
with all my devices in xenolinux.

The "machine" I am running on is "qemu", and it doesn't have emulation for
PCI. Therefore xenolinux is doing its ideprobes independent of the pci ide
code.
It is calling the routine "probe_irq_on" in irq.c, and it is failing with
the following messages:

ide: Assuming 50MHz system bus speed for PIO modes; override with idebus=xx
Kernel panic: Failed to obtain physical IRQ 127

"Probe_irq_on" is used to enable ALL unallocated irqs, the caller code will
then twig the device you are probing (in my case it is the ide drives for
ide0 disk, and ide0 cdrom) - and then will record the irq that actually got
the interrupt thus figuring out which irq belongs to which device.

The reasons it is failing seem to be the following:
1) The probe enables 127 physical IRQs (NR_PIRQS), but xen fails to bind any
pirq > 63. This is because sched.h only defines pirq_to_evtchn with a size
of 64
2) When I tried making that constant from 64->128, it still failed on IRQ 12
(which I think was already allocated to another device).

I was able to get much much further by setting "ide0=0x1f0,0x3f6,14
ide1=noprobe ide2=noprobe ide3=noprobe" on the command line. It still failed
much later on with an MMU update failure. I am currently tracking that one
down further before reporting it.


Barry Silverman



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