mirror.dongdigua.github.io/org/fix_tty.org

#+TITLE: [Custom Kernel] Fix TTY after Fedora 37 Upgrade
#+DATE: <2022-12-19 一>
#+DESCRIPTION: Xanmod

* What Happened
After switching to f37, something changed:
- [[./wayland.org::#dm][sddm]] don't work
- sway don't have environment variables
- v2rayA don't start automatically

but those are not vital.
One day I wanted to login to tty, it just stuck. However,  default kernel works.
I wonder how~ I wonder why~

But before this, I noticed some other scenario:
- old f36 kernel and kernel built on f36 won't boot
- newly built kernel don't have startup screen with fedora logo
- when I added a new kernel, the grub select the f37 kernel by default

I didn't take them seriously, until my kernel goes wrong as above.

How to fix that? is there any suspicious config I added?
So I rolled back to an older version of my config but still don't work.

* Ask for help
I think I can't solve this,
therefore, I asked for help at =#kernel= on libera.chat
(weechat is really great... to have English-only chat)

@@html:<details>@@
@@html:<summary>chat log</summary>@@
#+BEGIN_SRC text
<digua> hello, I made a custom kernel, but I cannot switch tty
<tdr> thats not usually a kernel problem.
<digua> but if I switch to fedora default kernel, it work
<tdr> did you include everything your init system uses/needs?
<tdr> its your init that needs to spawn the other tty getty's / logins
<tdr> so systemd or whatever init system youre using
<digua> what getty need to include?
<tdr> ok i guess i said im wrong there, it can be either
<jn> if you use the same userspace with both kernels, the next thing to check is the configs
<jn> /boot/config-* or /proc/config.gz
<jn> maybe there are differences there that explain the different outcomes
<tdr> there is a diff tool in the scripts directory too, much better than normal diff
<tdr> diffconfig
<tdr> digua, which distoro kernel did you replace?
<digua> fedora to xanmod
<tdr> i think some need stuff in the initramfs to get the muti tty stuff too
<digua> o I noticed one thinig in dmesg
<tdr> digua, doesnt fedora use plymoutth or smoeting in the ramdisk normally .. you may want to pull apart your old initramfs and look in there too
<digua> when I switch tty, dmesg says something about rfkill
<tdr> rfkill is radio on/off
<tdr> so wifi or bt or whatever
<digua> tdr, plymouth is the fedora logo support? i don't have that in my kernel
<digua> does it have an impact on tty?
<tdr> depeneds what <they> do with or around it
<tdr> there's no solid rules of what is done where or how, as long as requirements are met for <next step>

<digua> tdr, so I checked both initramfs, and I only found intel microcode, so now the problem isn't at initramds
<tdr> you didnt unpack it the right way
<tdr> if dracut made it, there are 2 parts
<digua> i use cpio -idv < file
<tdr> digua, https://www.thegeekdiary.com/centos-rhel-7-how-to-extract-initramfs-image-and-editview-it ... the skipcpio method
<tdr> digua,  /usr/lib/dracut/skipcpio  <your initramfs file> | zcat | cpio -ivd
<tdr> lsinitrd also works to see whats there without doing much else
<digua> thanks, I thought it can't contain only microcode :)
<tdr> it can be a chamber of "secrets" easy enough
<small> jn: hmm

<digua> I'm back! after a noon of compiling with ealier config
<digua> but tty STILL don't work, I think the f37 upgrade breaks it
<digua> tdr, so I think it's not my config issue :-|
<tdr> hrm i'd be cautious saying a distro released/tested kernel breaks your boot.  not saying its impossible, but i'd also try their stock config.
<tdr> specifically, their kernel and initramfs pair together.  before opening a bug with them
<digua> I remembered, when I upgraded to f37, the f36 kernel and kernel build on f36 all don't boot, so maybe I need to config based on the f37 default?
<digua> building with f37 config works fine, and I will reconfigure based on it :)
<digua> tdr, thank you for your generous help
#+END_SRC
@@html:</details>@@

Yeah, there *is* something that changed after f37 upgrade
and I'm still using the config I modified based on f36 one!

So I grabbed the f37 config at =/boot= and replaced =.config=,
then, without any modification, compile it.
/*It fucking worked!!!*/
also the startup logo (plymouth)

For I have [[https://dongdigua.github.io/kernel][recorded]] what I change I have made based on the default kernel,
it's not too difficult to reconfigure it.
The next step is to find out what is really going wrong...


* Thought
The book /Absolute OpenBSD/ says people should *not* build a custom OpenBSD kernel, that's right for OpenBSD.
Because it's application and kernel are together,
and  it have the magical [[https://man.openbsd.org/config.8][config(8)]] to modify the kernel biniary.

For Linux user, it's still good to have a configured kernel.