MIME-Version: 1.0
Date:   Mon, 20 Feb 2023 22:23:38 +0100
From:   Oleksandr Natalenko <oleksandr@natalenko.name>
To:     David Woodhouse <dwmw2@infradead.org>
Cc:     tglx@linutronix.de, kim.phillips@amd.com,
        Usama Arif <usama.arif@bytedance.com>, arjan@linux.intel.com,
        mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
        hpa@zytor.com, x86@kernel.org, pbonzini@redhat.com,
        paulmck@kernel.org, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org, rcu@vger.kernel.org, mimoja@mimoja.de,
        hewenliang4@huawei.com, thomas.lendacky@amd.com, seanjc@google.com,
        pmenzel@molgen.mpg.de, fam.zheng@bytedance.com,
        punit.agrawal@bytedance.com, simon.evans@bytedance.com,
        liangma@liangbit.com, Piotr Gorski <lucjan.lucjanov@gmail.com>
Subject: Re: [PATCH v9 0/8] Parallel CPU bringup for x86_64
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Hello.

On 20.02.2023 21:31, David Woodhouse wrote:
> On Mon, 2023-02-20 at 17:40 +0100, Oleksandr Natalenko wrote:
>> On pondělí 20. února 2023 17:20:13 CET David Woodhouse wrote:
>> > On Mon, 2023-02-20 at 17:08 +0100, Oleksandr Natalenko wrote:
>> > >
>> > > I've applied this to the v6.2 kernel, and suspend/resume broke on
>> > > my
>> > > Ryzen 5950X desktop. The machine suspends just fine, but on
>> > > resume
>> > > the screen stays blank, and there's no visible disk I/O.
>> > >
>> > > Reverting the series brings suspend/resume back to working state.
>> >
>> > Hm, thanks. What if you add 'no_parallel_bringup' on the command
>> > line?
>> 
>> If the `no_parallel_bringup` param is added, the suspend/resume
>> works.
> 
> Thanks for the testing. Can I ask you to do one further test: apply the
> series only as far as patch 6/8 'x86/smpboot: Support parallel startup
> of secondary CPUs'.
> 
> That will do the new startup asm sequence where each CPU finds its own
> per-cpu data so it *could* work in parallel, but doesn't actually do
> the bringup in parallel yet.

With patches 1 to 6 (including) applied and no extra cmdline params 
added the resume doesn't work.

> Does your box have a proper serial port?

No, sorry. I know it'd help with getting logs, and I do have a 
serial-to-USB cable that I use for another machine, but in this one the 
port is not routed to outside. I think I can put a header there as the 
motherboard does have pins, but I'd have to buy one first. In theory, I 
can do that, but that won't happen within the next few weeks.

P.S. Piotr Gorski (in Cc) also reported this: "My friend from CachyOS 
can confirm bugs with smpboot patches. AMD FX 6300 only shows 1 core 
when using smp boot patchset". Probably, he can reply to this thread and 
provide more details.

-- 
   Oleksandr Natalenko (post-factum)