Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: [BUGFIX][PATCH] Freezer, CPU hotplug, x86 Microcode: Fix task freezing failures | Date | Tue, 4 Oct 2011 21:49:30 +0200 |
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On Tuesday, October 04, 2011, Borislav Petkov wrote: > On Tue, Oct 04, 2011 at 03:46:53PM +0200, Borislav Petkov wrote: > > On Tue, Oct 04, 2011 at 06:45:12PM +0530, Srivatsa S. Bhat wrote: > > > I would like to propose a modified solution to the problem: > > > > > > Taking a CPU offline: > > > * Upon a CPU_DEAD notification, just like the code originally did, we free > > > the kernel's copy of the microcode and invalidate it. So no changes here. > > > > > > Bringing a CPU online: > > > * When a CPU_ONLINE or CPU_ONLINE_FROZEN notification is received, > > > a. If the userspace is not frozen, we request microcode from userspace and > > > apply it to the cpu. > > > > > > b. However if we find that the userspace is frozen at that moment, we defer > > > applying microcode now and register a callback function to be executed > > > immediately when the userspace gets thawed. This callback function would > > > request microcode from userspace and apply it to the cpu. > > > > No need for that if we can drop the whole re-requesting of ucode on > > CPU_ONLINE* (see my other mail). Let me run some tests before though. > > Ok, it looks good. I had one issue with what happens when there's no > ucode image but the ucode driver is a bit-hmm... and that case actually > magically works. > > So you can have my Acked- and Tested-by:'s for the AMD side - you still > need to test it on Intel with both microcode_ctl and the module un- and > loading so that you make sure you're not introducing regressions, if you > haven't done so yet, of course.
Cool, thanks.
I'd like to hear a voice from the Intel side too.
Thanks, Rafael
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