As mentioned in a recent post, I have uninstalled plymouth from some of my system. It is still there on my main desktop, but I’ll remove it there, too, before I next reboot.
What is plymouth
Plymouth is the software that provides the graphic splash screen during startup and shutdown. For opensuse 12.3, it slowly fades in the opensuse wallpaper background. It also handles the prompting for the encryption key for any encrypted partition. Plymouth is also activated during shutdown, where it presents a gradual fadeout of the opensuse background.
Opensuse began using plymouth with release 12.2. Before that, there was a static splash screen, with a superimposed progress bar. The plymouth screen certainly looks a lot nicer. And it handles the crypto prompting quite well. Plymouth is started from the “initrd” (initial ram disk) so that it can be in use before the file systems are mounted. And it continues right up until the graphic desktop is started.
Prompting for an encryption key might be initiated from the “initrd” if the root file system is part of an encrypted LVM. Or it might be initiated later if “/home” is the first encrypted file system to be mounted. Plymouth remembers what key was entered on the first request, and tries that key again for later encrypted file systems. So if all file systems use the same key, there is only one prompt.
Why remove plymouth?
I have never liked splash screens. I like to see the raw messages displayed on the screen during startup. They give me an idea of whether things are going normally, or whether there might be problem. In opensuse releases up to 12.1, I usually modified the boot command to disable the use of a splash screen.
With 12.2 and 12.3, I had left plymouth there until now, though I had considered removing it. Since I test beta releases, I considered plymouth to be part of what I was testing. However, my hand was forced recently, when I ran out of space in “/boot” (as previously posted). The software and data for plymouth add around 20M to the “initrd” file. So removing plymouth looked like a good way to solve my space problem for “/boot” while also removing the annoyance of a splash screen hiding all of those boot messages.
How to remove
In order to remove plymouth, I started Yast software management. There, I did a search for “plymouth”. And then I marked the first of the plymouth libraries (the first listed) for removal. A conflict resolution window popped up, mentioning 8 packages that depended on that library. I accepted the choice to also uninstall those. All but one of those packages were obviously part of plymouth. The other one, “suspend”, also turns out to be part of the plymouth suite.
Clicking “accept” I allowed Yast to go ahead and remove them. The removal was fast — too fast. It did not automatically rebuild the “initrd”. So I did that (as root) from the command line, by running “mkinitrd”.
I then rebooted, to test that all was well. And it was nice to see those messages appearing during system startup.
The encryption keys
The first system where I removed plymouth was using an encrypted LVM. The “mkinitrd” command put the necessary crypto software in the “initrd” so that the LVM is made available for mounting during boot.
I did have a question on what would happen with two or more encrypted partitions. So I went ahead and removed plymouth on a system that I had setup with encrypted “/home” and encrypted swap. With plymouth, I was only prompted once for the key on that system. What remained to be seen was whether I would be prompted twice after removing plymouth.
I followed similar removal steps. As before, I then ran “mkinitrd”. The output from “mkinitrd” did not mention LUKS encryption. That was bad news. It meant that the prompting for encryption keys would be done later, and I would probably be prompted twice. To solve this, I edited “/etc/crypttab”. The last column of each entry is for options. I entered “initrd” as an option in the lines for both “/home” and “swap”. This had worked in the past. However, the current man pages for “crypttab” no longer mention using “initrd” as an option, so I was not sure what would happen.
I ran “mkinitrd” again. This time the output was reassuring. It indicated that crypto for both partitions should be handled in the “initrd”. Then, rebooting as a test, I confirmed that it was working well. I was prompted only once for the encryption key, and this was followed by messages indicating that both partitions had been unlocked.
If you like a splash screen to hide the startup messages, then keep plymouth. If you prefer to see the messages, then I have described how to remove plymouth.