Messages in this thread | | | Date | Tue, 21 Feb 2023 11:54:50 +0000 | Subject | Re: [External] Re: [PATCH v9 0/8] Parallel CPU bringup for x86_64 | From | Usama Arif <> |
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On 21/02/2023 11:42, Oleksandr Natalenko wrote: > On 21.02.2023 11:47, Usama Arif wrote: >> On 21/02/2023 10:27, David Woodhouse wrote: >>> >>> On 21 February 2023 09:49:51 GMT, Oleksandr Natalenko >>> <oleksandr@natalenko.name> wrote: >>>> On 21.02.2023 10:06, David Woodhouse wrote: >>>>> Why does arch/x86/kernel/acpi/sleep.c::x86_acpi_suspend_lowlevel() set >>>>> >>>>> initial_gs = per_cpu_offset(smp_processor_id()) ? >>>>> >>>>> Would it not be CPU#0 that comes back up, and should it not get >>>>> per_cpu_offset(0) ? >>>> >>>> Wanna me try `initial_gs = per_cpu_offset(0);` too? >>> >> >> I think it might be smp_processor_id() and not 0 incase CPU0 was >> offline at the point the system was suspended? > > Is it even possible for CPU 0 to be offline, at least on x86? >
It is possible on x86 (using BOOTPARAM_HOTPLUG_CPU0), but I just read the Kconfig option and it says:
"resume from hibernate or suspend always starts from CPU0. So hibernate and suspend are prevented if CPU0 is offline."
so I guess switching to 0 should be ok.
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