Messages in this thread | | | From | Brian Gerst <> | Date | Wed, 1 Apr 2020 10:38:51 -0400 | Subject | Re: [PATCH v2] x86/smpboot: Remove 486-isms from the modern AP boot path |
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On Wed, Apr 1, 2020 at 8:14 AM Andrew Cooper <andrew.cooper3@citrix.com> wrote: > > On 01/04/2020 12:39, Brian Gerst wrote: > > On Wed, Apr 1, 2020 at 5:22 AM Andrew Cooper <andrew.cooper3@citrix.com> wrote: > >> On 31/03/2020 23:53, Brian Gerst wrote: > >>> On Tue, Mar 31, 2020 at 6:44 PM Andrew Cooper <andrew.cooper3@citrix.com> wrote: > >>>> On 31/03/2020 23:23, Brian Gerst wrote: > >>>>> On Tue, Mar 31, 2020 at 1:59 PM Andrew Cooper <andrew.cooper3@citrix.com> wrote: > >>>>>> Linux has an implementation of the Universal Start-up Algorithm (MP spec, > >>>>>> Appendix B.4, Application Processor Startup), which includes unconditionally > >>>>>> writing to the Bios Data Area and CMOS registers. > >>>>>> > >>>>>> The warm reset vector is only necessary in the non-integrated Local APIC case. > >>>>>> UV and Jailhouse already have an opt-out for this behaviour, but blindly using > >>>>>> the BDA and CMOS on a UEFI or other reduced hardware system isn't clever. > >>>>>> > >>>>>> We could make this conditional on the integrated-ness of the Local APIC, but > >>>>>> 486-era SMP isn't supported. Drop the logic completely, tidying up the includ > >>>>>> list and header files as appropriate. > >>>>>>
> >>>>> You removed x86_platform.legacy.warm_reset in the original patch, but > >>>>> that is missing in V2. > >>>> Second hunk? Or are you referring to something different? > >>> Removing the warm_reset field from struct x86_legacy_features. > >> Ok, but that is still present as the 2nd hunk of the patch. > > My apologies, Gmail was hiding that section of the patch because it > > was a reply to the original patch. For future reference, add the > > version number to the title when resubmitting a patch (ie. [PATCH > > v2]). > > Erm... is Gmail hiding that too? > > Lore thinks it is there: > https://lore.kernel.org/lkml/CAMzpN2g0LS5anGc7CXco4pgBHhGzc8hw+shMOg8WEWGsx+BHpg@mail.gmail.com/
Ugh, yes. I thought it was the title that Gmail threaded on, but it must be the In-Reply-To: header. Sorry for the confusion.
That said, I think the v1 patch is probably the better way to go (but adjusting the comments to include early Pentium-era systems without integrated APICs). Then the decision to drop support for external APICs could be a separate patch.
-- Brian Gerst
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