Messages in this thread | | | Date | Sat, 25 Apr 2009 12:30:11 +0200 | Subject | Re: [PATCH] x86 microcode: work_on_cpu and cleanup of the synchronization logic | From | Dmitry Adamushko <> |
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2009/4/24 Hugh Dickins <hugh@veritas.com>: > On Fri, 24 Apr 2009, Dmitry Adamushko wrote: >> 2009/4/24 Dmitry Adamushko <dmitry.adamushko@gmail.com>: >> > 2009/4/24 Hugh Dickins <hugh@veritas.com>: >> >> >> >> Good thinking, yes we can and do, unless I'm misinterpreting the >> >> evidence. Though P4 Xeon and Atom startup messages give the opposite >> >> impression, claiming to update all cpus from lower revision, more >> >> careful tests starting from "maxcpus=1" and then "echo 1 >online" >> >> (which, unless you've fiddled around putting the microcode_ctl'ed >> >> microcode.dat into /lib/firmware/intel-ucode/wherever, isn't able >> >> to update at online time on Intel) shows that the later onlined >> >> siblings already have the updated microcode applied to their >> >> previously onlined siblings. Which isn't surprising, but I'd >> >> been lulled into thinking the opposite by the startup sequence. > ... >> >> But then I wonder why behavior (the fact that all threads seem to >> upgrade to a newer version during the startup but they seem to already >> be 'up-to-date' if onlined later) during the startup is different... > > I believe it's because the module_init microcode_init() calls > sysdev_driver_register(), which does mc_sysdev_add() of (all possible?) > cpus, which for online cpus calls microcode_init_cpu(), which does > collect_cpu_info() then, if SYSTEM_RUNNING, request_microcode_fw() > and apply_microcode_on_target() (names with your patch applied). > > If the microcode driver is builtin (so gets here before SYSTEM_RUNNING), > or if it's for Intel with no firmware in /lib/firmware/intel-ucode/X-X-X > yet, the cpu_sig is thus obtained for all online cpus, before initscripts > run /sbin/microcode_ctl to update from /etc/microcode.dat successfully: > the "updated from revision" message shows uci->cpu_sig.rev as it > was saved earlier, rather than reevaluating it just before update. > > That's confusing for us, and confusing when resume shows updated from > high revision to same high revision (though, I think, the revision > should in fact have reverted during suspend); but might be even more > worrying to HT users if it were corrected (it would seem as if only > half their cpus got updated, when before all were). I don't know.
Perhaps, it doesn't make sense to cache 'cpu_sig' at all. I'll ponder on it a bit and send a new patch.
Thanks a lot for your feedback!
> >> Too pity that I can't see it with my setups (heh, I perhaps could play >> with it by actually downgrading cpus to older ucode). > > Please, Intel, ship this man some out-of-date hardware! > > (You're sure your cpus really are up-to-date? I thought several > of my boxes were, but then discovered a modinfo line in openSUSE > 11.1's /etc/init.d/microcode.ctl, which had been added since 10.3, > which was now disabling it when microcode driver built into kernel.) >
hmm, I downloaded - what seems to be - the recent .dat file from the Intel's site and run microcode_ctl (a binary, no additional scripts manually). I will check the site for updates again.
> > Hugh >
-- Best regards, Dmitry Adamushko
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