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Re: kern/60140: NetBSD 11.0-RC2 boots to black screen on Thinkpad X240 more often than not



The following reply was made to PR kern/60140; it has been noted by GNATS.

From: opensauce04%gmail.com@localhost
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: kern/60140: NetBSD 11.0-RC2 boots to black screen on Thinkpad
 X240 more often than not
Date: Sun, 29 Mar 2026 21:13:58 +0100

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 >   My guess would be that you could probably plug it back in as soon as
 >   the (green text) autoconfiguration messages start appearing.   If that
 >   doesn't work (if the boot were to hang at that time as soon as you plug
 >   in the charger) it would be a clue that the issue is related to unprocessed
 >   interrupts
 Plugging in the charger as soon as the green text appears works fine, it 
 consistently reaches the login prompt.
 >   On a boot that works, when you later plug in the charger,
 >   use either vmstat -w1  or  systat vm   and look at the interrupt rate.
 >   If you see many thousands (or more) of interrupts per second, continuously,
 >   that would be a good clue (but not seeing that means nothing.)
 I'm not quite sure how to read the values produced by these commands, 
 but the output doesn't seem to change in any meaningful way. The `flt` 
 value increases to ~3000 and the `in` value changes from around 30 to 
 100, before both then go back to their baselines, but I can get this to 
 happen by just doing stuff on the computer while it's running regardless 
 of the state of the charger.
 >     | it has an extremely high likelihood of failing.
 >   
 >   One other question worth asking is whether it makes any difference
 >   whether the laptop was powered off (as in shut down completely) before
 >   the boot, rather than just reset or a reboot.
 The behaviour is identical between rebooting / shutting down + booting. 
 The issue appears solely reliant on whether or not the laptop is 
 charging at the start of the boot process.
 >   Also perhaps whether
 >   it makes any difference if you interact with the firmware between starting
 >   the boot sequence and the firmware actually attempting an OS boot
 >   (that is if you enter the firmware setup mode, and then do the "save & exit"
 >   operation to boot, does that make any difference).
 This has no effect.
 >     |  I have no desktop environment installed on this device, and as I
 >     |  mentioned, this also happens with flashed USB installers, which also
 >     |  have no graphical environment.
 >   
 >   On a laptop there is always a graphical environment (or 99% of the time).
 
 Of course :) I meant to say that I don't have any X11 or Wayland session 
 configured to start at boot, so I just get dropped into the TTY when the 
 OS boots. Apologies if I was unclear.
 
 ----
 
 Is there anything else you'd like me to try/share to help investigate 
 the issue?
 
 
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     <blockquote type="cite"
       cite="mid:20260329191502.14B141A923E%mollari.NetBSD.org@localhost">
       <pre wrap="" class="moz-quote-pre"> My guess would be that you could probably plug it back in as soon as
  the (green text) autoconfiguration messages start appearing.   If that
  doesn't work (if the boot were to hang at that time as soon as you plug
  in the charger) it would be a clue that the issue is related to unprocessed
  interrupts </pre>
     </blockquote>
     Plugging in the charger as soon as the green text appears works
     fine, it consistently reaches the login prompt.
     <blockquote type="cite"
       cite="mid:20260329191502.14B141A923E%mollari.NetBSD.org@localhost">
       <pre wrap="" class="moz-quote-pre"> On a boot that works, when you later plug in the charger,
  use either vmstat -w1  or  systat vm   and look at the interrupt rate.
  If you see many thousands (or more) of interrupts per second, continuously,
  that would be a good clue (but not seeing that means nothing.)
 </pre>
     </blockquote>
     I'm not quite sure how to read the values produced by these
     commands, but the output doesn't seem to change in any meaningful
     way. The `flt` value increases to ~3000 and the `in` value changes
     from around 30 to 100, before both then go back to their baselines,
     but I can get this to happen by just doing stuff on the computer
     while it's running regardless of the state of the charger.<span
     style="white-space: pre-wrap">
 </span>
     <blockquote type="cite"
       cite="mid:20260329191502.14B141A923E%mollari.NetBSD.org@localhost">
       <pre wrap="" class="moz-quote-pre">   | it has an extremely high likelihood of failing.
  
  One other question worth asking is whether it makes any difference
  whether the laptop was powered off (as in shut down completely) before
  the boot, rather than just reset or a reboot.</pre>
     </blockquote>
     The behaviour is identical between rebooting / shutting down +
     booting. The issue appears solely reliant on whether or not the
     laptop is charging at the start of the boot process.
     <blockquote type="cite"
       cite="mid:20260329191502.14B141A923E%mollari.NetBSD.org@localhost">
       <pre wrap="" class="moz-quote-pre"> Also perhaps whether
  it makes any difference if you interact with the firmware between starting
  the boot sequence and the firmware actually attempting an OS boot
  (that is if you enter the firmware setup mode, and then do the "save &amp; exit"
  operation to boot, does that make any difference).
 </pre>
     </blockquote>
     This has no effect.<span style="white-space: pre-wrap"> </span>
     <blockquote type="cite"
       cite="mid:20260329191502.14B141A923E%mollari.NetBSD.org@localhost">
       <pre wrap="" class="moz-quote-pre">   |  I have no desktop environment installed on this device, and as I 
    |  mentioned, this also happens with flashed USB installers, which also 
    |  have no graphical environment.
  
  On a laptop there is always a graphical environment (or 99% of the time).</pre>
     </blockquote>
     <p>Of course :) I meant to say that I don't have any X11 or Wayland
       session configured to start at boot, so I just get dropped into
       the TTY when the OS boots. Apologies if I was unclear.</p>
     <p>----</p>
     <p>Is there anything else you'd like me to try/share to help
       investigate the issue?</p>
     <br>
   </body>
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