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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Mon, 26 Apr 2021 12:45:15 -0700
Message-ID: <CAHk-=wjvVMucgoAQKfi-x=jvYgKW1_LRmvnAfk3JGMkOSg9CQQ@mail.gmail.com>
Subject: Re: [BISECTED] 5.12 hangs at reboot
To:     Johannes Berg <johannes@sipsolutions.net>
Cc:     Harald Arnesen <harald@skogtun.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Mon, Apr 26, 2021 at 12:38 PM Johannes Berg
<johannes@sipsolutions.net> wrote:
>
> >
> > dmesg from 5.12 without the revert is attached.
>
> That's it? There it just hangs? Not even printing something about tasks
> getting stuck?

I assume the dmesg is from before trying to shut the system down.
Useful mainly to see what the hardware is, than to debug the hang
itself.

So it looks like it's an Atheros AR9462. That doesn't sound too unusual.

Getting a dmesg from the actual shutdown is tricky, because the system
is obviously no longer usable at that point. You tend to need serial
consoles etc.

Shutdown hangs can be a bit nasty to debug for that reason (similar to
suspend/resume issues).

                      Linus