Messages in this thread | | | From | "Han, Weidong" <> | Date | Wed, 22 Apr 2009 10:55:23 +0800 | Subject | RE: [patch 4/5] x2apic, IR: remove reinit_intr_remapped_IO_APIC() |
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Siddha, Suresh B wrote: > On Tue, 2009-04-21 at 00:01 -0700, Ingo Molnar wrote: >> * Han, Weidong <weidong.han@intel.com> wrote: >> >>> Siddha, Suresh B wrote: >>>> When interrupt-remapping is enabled, We are relying on >>>> setup_IO_APIC_irqs() to configure remapped entries in the IO-APIC, >>>> which comes little bit later after enabling interrupt-remapping. >>>> >>>> Meanwhile, Restore of old io-apic entries after enabling >>>> interrupt-remapping will not make the interrupts through io-apic >>>> functional anyway. >>>> >>>> So remove unnecessary reinit_intr_remapped_IO_APIC(). >>>> >>>> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> >>>> Cc: Weidong Han <weidong.han@intel.com> >>>> --- >>>> >>>> Index: tip/arch/x86/include/asm/io_apic.h >>>> =================================================================== >>>> --- tip.orig/arch/x86/include/asm/io_apic.h >>>> +++ tip/arch/x86/include/asm/io_apic.h >>>> @@ -166,8 +166,6 @@ extern void free_ioapic_entries(struct I >>>> extern int save_IO_APIC_setup(struct IO_APIC_route_entry >>>> **ioapic_entries); extern void mask_IO_APIC_setup(struct >>>> IO_APIC_route_entry **ioapic_entries); extern int >>>> restore_IO_APIC_setup(struct IO_APIC_route_entry **ioapic_entries); >>>> -extern void reinit_intr_remapped_IO_APIC(int intr_remapping, >>>> - struct IO_APIC_route_entry **ioapic_entries); >>>> >>>> extern void probe_nr_irqs_gsi(void); >>>> >>>> Index: tip/arch/x86/kernel/apic/apic.c >>>> =================================================================== >>>> --- tip.orig/arch/x86/kernel/apic/apic.c >>>> +++ tip/arch/x86/kernel/apic/apic.c >>>> @@ -1416,8 +1416,6 @@ end_restore: >>>> * IR enabling failed >>>> */ >>>> restore_IO_APIC_setup(ioapic_entries); >>>> - else >>>> - reinit_intr_remapped_IO_APIC(x2apic_preenabled, ioapic_entries); >>> >>> Whether IR enabling succeeds or fails, it always needs to restore >>> old IOAPIC entries. Due to removing reinit_intr_remapped_IO_APIC >>> here, it needs to also remove the "if (ret)" before >>> restore_IO_APIC_setup(ioapic_entries); >> >> Ok - i skipped this patch for now. > > Let me clarify what I am doing in this patch: > > When interrupt-remapping is enabled, IO-APIC entries need to be setup > in the re-mappable format (pointing to interrupt-remapping table > entries setup by the OS). This remapping configuration is happening > in the same place where we traditionally configure IO-APIC (i.e., in > setup_IO_APIC_irqs()). > > So when we enable interrupt-remapping successfully, there is no need > to restore old io-apic RTE entries before we actually do a complete > configuration shortly in setup_IO_APIC_irqs(). Old IO-APIC RTE's may > be in traditional format (non re-mappable) or in re-mappable format > pointing to interrupt-remapping table entries setup by BIOS. Restoring > both of these will not make IO-APIC functional. We have to rely on > setup_IO_APIC_irqs() for proper configuration by OS. > > So I am removing this unnecessary and broken step. > > When enabling interrupt-remapping is not successful, we are doing > plain restore of old RTE's (which will still work as we went back to > original no-remapping state). Complete IO-APIC configuration will be > done shortly in setup_IO_APIC_irqs(). >
Clear explanation. I misunderstood it. This patch is fine.
Regards, Weidong
> thanks, > suresh
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