From: Suresh Siddha Date: Thu, 25 Aug 2011 19:01:11 +0000 (-0700) Subject: x86, kdump, ioapic: Reset remote-IRR in clear_IO_APIC X-Git-Tag: v3.2-rc1~167^2~2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1e75b31d638d5242ca8e9771dfdcbd28a5f041df;p=pandora-kernel.git x86, kdump, ioapic: Reset remote-IRR in clear_IO_APIC In the kdump scenario mentioned below, we can have a case where the device using level triggered interrupt will not generate any interrupts in the kdump kernel. 1. IO-APIC sends a level triggered interrupt to the CPU's local APIC. 2. Kernel crashed before the CPU services this interrupt, leaving the remote-IRR in the IO-APIC set. 3. kdump kernel boot sequence does clear_IO_APIC() as part of IO-APIC initialization. But this fails to reset remote-IRR bit of the IO-APIC RTE as the remote-IRR bit is read-only. 4. Device using that level triggered entry can't generate any more interrupts because of the remote-IRR bit. In clear_IO_APIC_pin(), check if the remote-IRR bit is set and if so do an explicit attempt to clear it (by doing EOI write on modern io-apic's and changing trigger mode to edge/level on older io-apic's). Also before doing the explicit EOI to the io-apic, ensure that the trigger mode is indeed set to level. This will enable the explicit EOI to the io-apic to reset the remote-IRR bit. Tested-by: Leonardo Chiquitto Signed-off-by: Suresh Siddha Fixes: https://bugzilla.novell.com/show_bug.cgi?id=701686 Cc: Rafael Wysocki Cc: Maciej W. Rozycki Cc: Thomas Renninger Cc: jbeulich@novell.com Cc: yinghai@kernel.org Link: http://lkml.kernel.org/r/20110825190657.157502602@sbsiddha-desk.sc.intel.com Signed-off-by: Ingo Molnar --- Reading git-diff-tree failed