Messages in this thread | ![/](/images/icornerl.gif) | | Date | Tue, 21 Feb 2023 10:47:31 +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 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?
> Hm, yes please. There's another one to make zero on the next line up, I think? > >>> Or maybe we should just set up smpboot_control for the CPU to find its >>> own stuff, *even* on waking. Since the structures are already set up, >>> it isn't like a clean boot. >>> >>> If you let it boot in parallel mode, what if you just *remove* the line >>> that sets smpboot_control=0 ? >> >> If the `smpboot_control = 0;` line in arch/x86/kernel/acpi/sleep.c::x86_acpi_suspend_lowlevel() is commented out, and the system is booted in parallel mode, then suspend/resume works. > > Well that's entertaining. Now, can we come up with any theory which doesn't leave us wondering why it ever worked in the first place...?
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