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Message-ID: <9e770151-698c-0efe-8ea2-495f1ae54931@infradead.org>
Date:   Thu, 6 Jul 2023 18:48:48 -0700
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Subject: Re: Fwd: unable to boot when monitor is attached
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To:     "Dr. David Alan Gilbert" <linux@treblig.org>,
        Bagas Sanjaya <bagasdotme@gmail.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Johan Hovold <johan@kernel.org>,
        primalmotion <primalmotion@pm.me>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux USB <linux-usb@vger.kernel.org>
References: <5eb57bfe-94a4-136b-497e-deeb31846db1@gmail.com>
 <ZKdgMs2ChLnJ3U8n@gallifrey>
From:   Randy Dunlap <rdunlap@infradead.org>
In-Reply-To: <ZKdgMs2ChLnJ3U8n@gallifrey>
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On 7/6/23 17:45, Dr. David Alan Gilbert wrote:
> * Bagas Sanjaya (bagasdotme@gmail.com) wrote:
>> Hi,
>>
>> I notice a regression report on Bugzilla [1]. Quoting from it:
>>
>>>
>>> In the latest 6.3 and 6.4, it is impossible for me to boot my laptop if my DELL U2720Q monitor is plugged in (USB-C). I have to unplug it, then boot. As soon as the first second of boot went through, I can plug in my monitor and there is no issue afterward. There is no issue waking up after suspend. Only when it boots.
>>>
>>> See the attached pictures of the trace. The trace itself seems random (at least to me :)). I tried several things, like removing any attached USB devices from the monitor built-in USB-hub, but that does not change anything. (there is a keyboard and trackpad attached).
>>
>> See Bugzilla for the full thread.
>>
>> Unfortunately, the reporter can only provide photos of kernel trace
>> (as he doesn't have any other means to extract kernel logs, maybe
>> connecting over serial helps; see Bugzilla for these attachments).
> 
> I note the photos have 'crud' at the bottom; as if something interesting
> is in the video ram; perhaps something is freaked out by this nice 4k
> monitor and some useful data structures are ending up in video ram.
> 
> (Also note it's a librem with pureboot)
> 
> Dave
> 
>>
>> Anyway, I'm adding it to regzbot so that it doesn't fall through
>> cracks unnoticed:
>>
>> #regzbot introduced: v6.1..v6.3 https://bugzilla.kernel.org/show_bug.cgi?id=217637
>> #regzbot title: unable to boot with Dell U2720Q monitor attached
>>
>> Thanks.
>>
>> [1]: https://bugzilla.kernel.org/show_bug.cgi?id=217637

So what are __pfx_worker_thread and __pfx_kthread?
Where are they from?

-- 
~Randy