[Hardy][Intrepid] SRU request (assign IRQ0 vector bit)

Tim Gardner tim.gardner at canonical.com
Tue Sep 30 14:22:52 UTC 2008

Stefan Bader wrote:
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/276334
> SRU justification:
> Impact: Repeatedly loading and unloading a driver that uses a non-shared IRQ
> (always the case for MSI) will eventually assign the vector used by IRQ0
> (timer). This is because IRQ0 is setup early in the IO_APIC (32bit) code
> without marking the associated bit in the map of used vectors. This is a
> specific problem in the 32bit code of the IO APIC.
> Fix: patch attached (submitted upstream, not accepted, yet)
> Testcase: 32bit system with IO APIC in use. Unload and load a driver which does
> not share its IRQ repeatedly. After around 163 cycles cat /proc/interrupts will
> not show any new interrupts on IRQ0 and the system sometimes starts to freeze
> until any key is hit (trigger some other interrupt).
> This has a dependency to the MSI-X allocation bug which also needs to be fixed.
> https://bugs.edge.launchpad.net/ubuntu/+source/linux/+bug/273103


Tim Gardner tim.gardner at canonical.com

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