Messages in this thread | | | From | "Yu, Fenghua" <> | Date | Mon, 7 Nov 2011 13:02:54 -0800 | Subject | RE: [PATCH 6/8] x86, topology.c: Enable CPU0 online/offline |
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> >> And you forgot poweroff and reboot, which have similar dependencies > on > >> some machines. That whole low level ACPI stuff is sensitive. > > > > I tested poweroff, shutdown, and reboot with various reboot_type on a > few different platforms. I haven't seen poweroff and reboot issues > after CPU0 is offline. > > > > Do you have specific platforms that I can test poweroff and reboot > dependency on CPU0? > > > Or we just assume there are some platforms out there that depend on > CPU0 for poweroff/reboot? > > A classic Linux/ACPI failure happened when HT first shipped. > Some platforms stopped powering off or rebooting 50% of the time. > > It turned out that SMM on those machines assumed > it would be triggered from CPU0 and not CPU1. > > the original code should have worked, of course, > and most of the time it did -- but some systems broke. > The same will probably happen here.
Thanks for your info on poweroff/reboot and CPU0.
I wrote a statement in the cpu-hotplug.txt doc in newer patch set:
"It's said poweroff/reboot may depend on BSP on some machines although I haven't seen any poweroff/reboot failure so far after BSP is offline on a few tested machines." "Please let me know if you know or see any other dependencies of BSP."
If we know a specific model of machine can't poweroff/reboot after CPU0 is offline, I can do something like put that machine in a black list in the poweroff/reboot path to let user online CPU0 before poweroff/reboot.
Hopefully this is a temp OK solution for the patch set to get in kernel and let people report any poweroff/reboot or any other dependencies on CPU0.
Thanks.
-Fenghua
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