Re: Weird characters in virtual terminal consoles from (CTRL-ALT) F2 to F6 and over F7
Ciao Gianluca,
On Wed, Dec 17, 2025 at 09:42:17AM +0100, Gianluca Renzi wrote:
> 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.
Ack, for now we put ourself then in wait position unless someone else
affected can do the same bisect procedure and narrow down the
problematic commit earlier.
Thank you,
Regards,
Salvatore
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