Messages in this thread | | | Date | Wed, 14 Aug 2013 13:11:05 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH] x86, apic: Enable x2APIC physical when cpu < 256 native |
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* Youquan Song <youquan.song@linux.intel.com> wrote:
> > In order to make sure the patch without involving unexpected issues beyond > > I can understand, I will confirm with our expert about it. > > > > so please pend the patch going to mainline. If the patch can move on, I > > think I will also provide other patch changing, like direct EOI. > > Hi Yinghai and Ingo, > > I have confirmed with our experts about it. x2APIC without interrupt > remapping is not architecture and no guarantee it will work in future. > > What's more, 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. > > Ingo, please drop the patch in -tip tree. > 3d1acb49d22fbbae96524040e9e2d4cbbb3adbef "x86/apic: Enable x2APIC > physical mode on native hardware too, when there are fewer than 256 > CPUs"
Ok, dropped it - it was still the tail commit.
> Sorry for making fuss here and it is my fault.
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.
Thanks,
Ingo
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