On Sat, Aug 17, 2013 at 09:42:56AM +0200, Ingo Molnar wrote:
>
> * Youquan Song <youquan.s...@linux.intel.com> wrote:
>
> > > No problem - you might want to send another patch adding some comments to
> > > the code, explaining why we don't switch to physical mode, quoting from
> > > the SDM and so.
> >
> > Here is the revert patch.
> >
> > Subject: [PATCH] Revert "x86/apic: Enable x2APIC physical mode on native
> > hardware too, when there are fewer than 256 CPUs"
> >
> > x2APIC without interrupt remapping is not architecture and no guarantee it
> > will work in future.
> > There are some words in SDM3, 10.12.7 Initialization by System
> > Software Routing of device interrupts to local APIC units operating in
> > x2APIC mode requires use of the interrupt-remapping architecture
> > specified in the Intel Virtualization Technology for Directed I/O,
> > Revision 1.3. Because of this, BIOS must enumerate support for and
> > software must enable this interrupt remapping with Extended Interrupt
> > Mode Enabled before it enabling x2APIC mode in the local APIC units.
> >
> > This reverts commit 3d1acb49d22fbbae96524040e9e2d4cbbb3adbef, do not use
> > x2apic_pysical mode if interrupt remapping is not enabled even at CPU
> > number fewer than 256.
> >
> > Signed-off-by: Youquan Song <youquan.s...@intel.com>
> > ---
> > arch/x86/kernel/apic/apic.c | 7 +++++--
> > 1 files changed, 5 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
> > index d9dd5a6..eca89c5 100644
> > --- a/arch/x86/kernel/apic/apic.c
> > +++ b/arch/x86/kernel/apic/apic.c
> > @@ -1622,8 +1622,11 @@ void __init enable_IR_x2apic(void)
> > goto skip_x2apic;
> >
> > if (ret < 0) {
> > - /* IR is required if there is APIC ID > 255 */
> > - if (max_physical_apicid > 255) {
> > + /* IR is required if there is APIC ID > 255 even when running
> > + * under KVM
> > + */
> > + if (max_physical_apicid > 255 ||
> > + !hypervisor_x2apic_available()) {
>
> Firstly, please use the customary (multi-line) comment
> style:
>
> /*
> * Comment .....
> * ...... goes here.
> */
>
> specified in Documentation/CodingStyle.
This keeps popping up. Maybe it should be in checkpatch, Joe?
With the special handling of net/ and drivers/net/ of course.
--
Regards/Gruss,
Boris.
Sent from a fat crate under my desk. Formatting is fine.
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