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.
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You might want to drop this from future replies, this is a public
mailinglist ;-)
Rgards,
Salvatore
