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Re: Weird characters in virtual terminal consoles from (CTRL-ALT) F2 to F6 and over F7

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On 12/17/25 09:34, Salvatore Bonaccorso wrote:
> On Wed, Dec 17, 2025 at 08:24:59AM +0100, Gianluca Renzi wrote:
>> Hello list,
>>
>> as stated in this reddit's issue
>> https://www.reddit.com/r/debian/comments/1pnrm5t/comment/nugj9wc/?%24deep_link=true&context=1&correlation_id=2b4b5f38-db9c-5ace-95e8-d47408cf9fae&ref=email_comment_reply&ref_campaign=email_comment_reply&ref_source=email&%243p=e_as&_branch_match_id=1529734982500663144&utm_medium=Email+Amazon+SES&_branch_referrer=H4sIAAAAAAAAA31O2U7DMBD8mvQtCc0BDVKEkFB%2Fw%2FKxSbb40tppygvfzqaFVyRbmp2dmZ0l55he65rAGMyVjLGy6D%2FrNr4VTdfGEYRMB4aBcEYvrVjJjsvuKtr3ojnz27at%2BvXr4Jgg%2FgYUSs%2BAKQc%2BJ4bH6Mn1mVGkoCw4sWFexBUpr5ysg0%2FBQmJwBQ58bCXL%2FTpfhk3v51q%2B2DedAYhib1q0H5lWKJpntme4ZSaO94kIrMwYvEDDZKM61U%2FtqTRq0GUvNZRDDzx2L93TSU%2FDJPcUgonF4CTuhe7VBUG0X4%2Bd0NJFibP%2FV5TCShr%2BJIdv5oAI%2FSwUhS0BjWdkLtx%2BACEnHTd%2FAQAA
>>
>> there is a bug since last kernel update.
>>
>> My virtual consoles from tty2 to tty6 are covered with the copyright symbol.
>> I can still log in to the terminal although everything is illegible. After
>> logging in, I did an ls -a command to my directory. The output is in color.
>> The copyright symbols is obscuring the text. Please have a look at the
>> attachment.
>>
>> Switching back to older kernel the bug disappears.
>>
>> linux kernel 5.10.0-36-amd64 NO BUG
>>
>> linux kernel 5.10.0-37-amd64 BUG
>>
>> Here is the diff from the two kernel configuration files:
>>
>> diff -Nru /boot/config-5.10.0-36-amd64 /boot/config-5.10.0-37-amd64
>> --- /boot/config-5.10.0-36-amd64    2025-09-29 13:28:35.000000000 +0200
>> +++ /boot/config-5.10.0-37-amd64    2025-12-11 18:55:57.000000000 +0100
>> @@ -1,6 +1,6 @@
>>   #
>>   # Automatically generated file; DO NOT EDIT.
>> -# Linux/x86 5.10.244 Kernel Configuration
>> +# Linux/x86 5.10.247 Kernel Configuration
>>   #
>>   CONFIG_CC_VERSION_TEXT="gcc-10 (Debian 10.2.1-6) 10.2.1 20210110"
>>   CONFIG_CC_IS_GCC=y
>> @@ -25,7 +25,7 @@
>>   # CONFIG_COMPILE_TEST is not set
>>   CONFIG_LOCALVERSION=""
>>   # CONFIG_LOCALVERSION_AUTO is not set
>> -CONFIG_BUILD_SALT="5.10.0-36-amd64"
>> +CONFIG_BUILD_SALT="5.10.0-37-amd64"
>>   CONFIG_HAVE_KERNEL_GZIP=y
>>   CONFIG_HAVE_KERNEL_BZIP2=y
>>   CONFIG_HAVE_KERNEL_LZMA=y
>> @@ -2379,9 +2379,7 @@
>>   CONFIG_BLK_DEV_RAM=m
>>   CONFIG_BLK_DEV_RAM_COUNT=16
>>   CONFIG_BLK_DEV_RAM_SIZE=16384
>> -CONFIG_CDROM_PKTCDVD=m
>> -CONFIG_CDROM_PKTCDVD_BUFFERS=8
>> -# CONFIG_CDROM_PKTCDVD_WCACHE is not set
>> +# CONFIG_CDROM_PKTCDVD is not set
>>   CONFIG_ATA_OVER_ETH=m
>>   CONFIG_XEN_BLKDEV_FRONTEND=m
>>   CONFIG_XEN_BLKDEV_BACKEND=m
>>
>> Please let me know how to proceed further.
> Ideally you bisect now the changes to identify which commit breaks.
> That would involve compiling and testing a few kernels:
>
>      git clone --single-branch -b linux-5.10.y https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
>      cd linux-stable
>      git checkout v5.10.244
>      cp /boot/config-$(uname -r) .config
>      yes '' | make localmodconfig
>      make savedefconfig
>      mv defconfig arch/x86/configs/my_defconfig
>
>      # test 5.10.244 to ensure this is "good"
>      make my_defconfig
>      make -j $(nproc) bindeb-pkg
>      ... install the resulting .deb package and confirm it successfully boots / problem does not exist
>
>      # test 5.10.247 to ensure this is "bad"
>      git checkout v5.10.244
>      make my_defconfig
>      make -j $(nproc) bindeb-pkg
>      ... install the resulting .deb package and confirm it fails to boot / problem exists
>
> With that confirmed, the bisection can start:
>
>      git bisect start
>      git bisect good v5.10.244
>      git bisect bad v5.10.247
>
> In each bisection step git checks out a state between the oldest
> known-bad and the newest known-good commit. In each step test using:
>
>      make my_defconfig
>      make -j $(nproc) bindeb-pkg
>      ... install, try to boot / verify if problem exists
>
> and if the problem is hit run:
>
>      git bisect bad
>
> and if the problem doesn't trigger run:
>
>      git bisect good
>
> . Please pay attention to always select the just built kernel for
> booting, it won't always be the default kernel picked up by grub.
>
> Iterate until git announces to have identified the first bad commit.
>
> Then provide the output of
>
>      git bisect log
>
> In the course of the bisection you might have to uninstall previous
> kernels again to not exhaust the disk space in /boot. Also in the end
> uninstall all self-built kernels again.

Got it.

At the moment I am very busy at work, so I cannot have the time to test 
them all.

After Dec 23th I will do the tests on my home machine. Basically it's 
the same OS and kernel and same hardware, but a little older.

AFAIK the issue is in the production machine, that's a different 
hardware at all (it's a MiniPC against a Dell Precision 3630 Workstation)

Maybe both have an integrated Intel Graphic Card.

I will check later.

Thank you in advance,


>> Invito alla riservatezza:
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>> che  ai  sensi  del  D.Lgs.196/2003  e adeguamento del nuovo Regolamento
>> Europeo nr. 679/2016
>>
>> Invitation to privacy:
>> This  request  for  an  e-mail  quote  includes   personal  and  private
>> information. Making its content known to anyone other than the recipient
>> is forbidden.  Unauthorized  recipients are kindly requested to maintain
>> secrecy,  promptly  inform  the sender of the wrong reception and delete
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>> Spreading,  distributing  and  /  or copying the provided information by
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>> Regulation n. 679/2016
> You might want to drop this from future replies, this is a public
> mailinglist ;-)
>
> Rgards,
> Salvatore

I did it right now.

;-)

Regards,

Gianluca

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Weird characters in virtual terminal consoles from (CTRL-ALT) F2 to  F6 and over F7 Gianluca Renzi <gianlucarenzi@eurek.it> - 2025-12-17 09:00 +0100
  Re: Weird characters in virtual terminal consoles from (CTRL-ALT) F2  to F6 and over F7 Salvatore Bonaccorso <carnil@debian.org> - 2025-12-17 09:40 +0100
    Re: Weird characters in virtual terminal consoles from (CTRL-ALT) F2  to F6 and over F7 Gianluca Renzi <gianlucarenzi@eurek.it> - 2025-12-17 10:10 +0100
      Re: Weird characters in virtual terminal consoles from (CTRL-ALT) F2  to F6 and over F7 Salvatore Bonaccorso <carnil@debian.org> - 2025-12-17 10:40 +0100
    Re: Weird characters in virtual terminal consoles from (CTRL-ALT) F2  to F6 and over F7 Camaleón <noelamac@gmail.com> - 2025-12-17 16:40 +0100
      Re: Weird characters in virtual terminal consoles from (CTRL-ALT) F2  to F6 and over F7 Gianluca Renzi <gianlucarenzi@eurek.it> - 2025-12-17 17:10 +0100

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