No GRUB menu (black screen) after latest update

User Support General
1

Hi,

I am experiencing a strange issue. This is a 4.2.4 system.

I have just updated dom0 and templates successfully. Then rebooted the machine. - Regular procedure.

What is new and strange:

Upon booting there is no more GRUB menu. Just a blank black screen that stays for a while and then takes me to the usual disk encryption password prompt.

This might be a bug.
How can I diagnose what is going on?
Is anyone else experiencing this?

2

Maybe it’s the timeout that got set to 0? Try cat /etc/default/grub | grep GRUB_TIMEOUT in dom0.

3

Pet peeve of mine: you don’t need cat most of the times (the command, not the animal! that is a completley different discussion) : grep GRUB_TIMEOUT /etc/default/grub

4

Pet peeve of mine: people complaining about additional cat invocations :slight_smile: . I’d argue that the cat ... | grep pipeline is actually more in line with *nix bash-fu, as instead of learning every command’s file-read syntax (different for grep, sed, read and all other utilities), you have a simple solution that you can apply everywhere without mental overhead :).

5
Off-topic-ish pet peeve discussion adding weight to the <don't use cat> argument

Running cat FILE | … is slower! Those lost milliseconds add up quickly :smile:

[user@dom0 ~]$ time ( for aa in {1..1000} ; do grep -q GRUB_TIMEOUT /etc/default/grub; done )

real  0m2.808s
user  0m0.652s
sys 0m2.271s
[user@dom0 ~]$ time ( for aa in {1..1000} ; do grep -q GRUB_TIMEOUT /etc/default/grub; done )

real  0m2.856s
user  0m0.701s
sys 0m2.269s
[user@dom0 ~]$ time ( for aa in {1..1000} ; do grep -q GRUB_TIMEOUT /etc/default/grub; done )

real  0m2.941s
user  0m0.722s
sys 0m2.331s
[user@dom0 ~]$ time ( for aa in {1..1000} ; do cat /etc/default/grub | grep -q GRUB_TIMEOUT ; done )

real  0m3.766s
user  0m1.312s
sys 0m4.924s
[user@dom0 ~]$ time ( for aa in {1..1000} ; do cat /etc/default/grub | grep -q GRUB_TIMEOUT ; done )

real  0m3.730s
user  0m1.347s
sys 0m4.922s
[user@dom0 ~]$ time ( for aa in {1..1000} ; do cat /etc/default/grub | grep -q GRUB_TIMEOUT ; done )

real  0m3.746s
user  0m1.337s
sys 0m4.949s
[user@dom0 ~]$
6

Did you find the answer?

If you can log in, it might be worth looking through the early kernel messages in Dom0:
sudo journalctl -b 0 | less

Maybe a graphics problem, although it’s not obvious why it would affect grub. Did you change any hardware recently?

There seem to have been a few people having trouble with Nvidia graphics at boot… is that your case?

I refrain from entering the cat wars… for now! :slight_smile:

7

Did you find the answer?

No. Both questions remain without an answer.
However, this thing got magically self-fixed (without applying any next update). No idea how. As I said, I have not touched anything.

If you can log in, it might be worth looking through the early kernel messages in Dom0:
sudo journalctl -b 0 | less

I already tried that before posting here. No useful info.

Maybe a graphics problem, although it’s not obvious why it would affect grub.

I thought about that too.

Did you change any hardware recently?

No. No changes whatsoever.

There seem to have been a few people having trouble with Nvidia graphics at boot… is that your case?

No discrete graphics here. It’s a NitroPC.

8

Maybe it’s the timeout that got set to 0?

No. The timeout was there. The menu wasn’t.