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Nix Packages collection & NixOS
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Enable grub debug output by default #62905

Closed deliciouslytyped closed 10 months ago

deliciouslytyped commented 5 years ago

Apparently grub has a grub_dprintffunction that's used for some manner of debug output. I Could we enable showing it by default?

davidak commented 5 years ago

I think most desktop users want a start without annoying messages. So i would not enable it by default, at least when boot.plymouth.enable = true;. But an option to enable it is useful.

deliciouslytyped commented 5 years ago

I don't mean this to sound snarky: Should we hide the nixos stage1/etc output as well then?

deliciouslytyped commented 5 years ago

My rationale is that it's usually harder to enable boot debug stuff when your system is failing to boot - but if you've explicitly chosen boot eye candy/hiding information over boot output, sure why not I guess. The ideal case would be if the eye candy can fall back to showing the failure information on failure.

davidak commented 5 years ago

Should we hide the nixos stage1/etc output as well then?

sure (https://github.com/NixOS/nixpkgs/issues/32556)

The ideal case would be if the eye candy can fall back to showing the failure information on failure.

yes, it would be useful when the system fails to boot. but on NixOS you can just start with previous configuration, so less important than with other distros.

deliciouslytyped commented 5 years ago

Rollbacks don't necessarily fix filesystem configuration issues. E.g. when you're migrating to ZFS. Edit: Ideally this probably wouldn't be a problem because you wouldn't transition your system in an unsafe manner, however it's precisely the non-ideal situations where things like this would help more, I think.

deliciouslytyped commented 5 years ago

FWIW I haven't actually had a chance to test this functionality, which would be important in this going forward in any case. Edit: To clarify, though i think samueldr will comment shortly: at the least I just want something more than getting dumped in a grub rescue prompt and "lol fix me bro."

samueldr commented 5 years ago

It's unclear in what way this is printed, from my research, it might expect to be printed to a serial port. I haven't been able to find documentation as apparently some of these things are willfully undocumented.

Configuring it to use debug print by default is probably a bad idea. The main issue would be the firehose of debugging text, which is not necessarily helpful.

Another issue, yet untested, is that when grub prints things, like error messages, it will do it in an intrusive way. When developing the installer image's boot menu, I found out that any error print in their script will pause the menu to show you the errors, even if they are expected and benign under ifconditionals. If they are printed using the same system, it would likely be an issue to users.

What could be done, instead, is to simplify installation of a debug-enabled grub to the system. Either as configured in the NixOS configuration, or even out-of-band by replacing a Grub from the ESP/legacy offsets. (The latter allowing one not to mount a complex system in the installer only to switch to debug mode.)

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