On 5/9/19 12:55 AM, Chris Murphy wrote:
On Wed, May 8, 2019, 4:50 AM Panu Matilainen <pmatilai@xxxxxxxxxx
<mailto:pmatilai@xxxxxxxxxx>> wrote:
Nicolas' point is that the rescue boot entry only works in a limited
number of scenarios.
I'm not sure which of three 'rescue' options is being discussed.
grub rescue appears when normal.mod can't be loaded, and means the menu
can't be displayed. This thread's bug results in this rescue.
Okay, I've no idea what that is, unless it simply means the grub prompt.
Since circa Fedora 19, there is a GRUB menu entry 'Rescue' option which
boots a "no host only" initramfs. If you see the option, you don't have
the bug under discussion.
AIUI this was the rescue mode that was being "critisized" here, in that
it only works in limited scenarios. I for one have never found any use
for it, but of course that doesn't mean a thing, it's nice that it's there.
Install media, dvd and netinst, have a bootloader submenu option for
Troubleshooting, that leads to an option Rescue a Fedora system, which
actually launches anaconda with app option 'inst.rescue' that helps
find, assemble and mount a Fedora installation or even just provide a
shell with all the CLI programs normally available for installs
including fsck, mkfs, various FS debug tools, etc.
And in some cases the rescue media IS needed to fix this particular
issue as well. For example my box never got to the grub prompt at all,
it was busy reboot-looping, probably due to negletting to reinstall
grub
in almost a decade. Others have pointed out other "completely broken"
symptoms.
I don't think that's this bug. It suggests the core.img embedded in
either the MBR gap or BIOSBoot partition has a serious bug or that the
computer firmware has a serious bug. Somehow is can neither load
blscfg.mod (this bug) and can't run it's own rescue mode (not this bug).
That would be super tedious to track down. And interestingly, would
potentially be masked by always updating the bootloader between major
upgrades (makes bootloader a moving Target). But if no one ever tracks
it down, which includes the even more tedious requirement of localy
building GRUB from source and reproducing the bug (because Fedora's GRUB
is so substantially modified from upstream that upstream will always
reject Fedora bugs), it won't get fixed.
Sure. I don't know what the rebooting loop was, but clearly it was
related to "this bug" because the bootloader has been working fine for
years until it got completely broken by the upgrade to F30. I've never
seen anything like that, ever. And certainly it was affected by "this
bug" too because of the ages old boot loader.
I guess we'll never find out because I wouldn't know the exact steps to
reproduce it even if I wanted to.
I admit, we've already failed if we're at grub rescue, letter alone in a
reboot cycle. But the latter sounds hardware (firmware) specific.
Difficult no matter what.
Really, if you don't even get a menu from grub, how many people are
going to be able to work it from there?
I think 1 in 10. Just a guess. That's probably generous.
Even if there was another
computer comfortably nearby for googling, I wouldn't bother even
trying.
Much easier to grab that rescue image, which thank goodness is there
still.
I don't know what rescue image is.
The bug this thread is about, if you hit it, you do not get a GRUB menu.
To me, rescue image means install media with Rescue boot option i.e.
anaconda inst.rescue.
Indeed, and without it I would've been lost on a few occasions,
including this. I dont think there's an actual disagreement anywhere in
here, just a side-track related to the awareness of thees various rescue
modes and their relative powers of rescue, or lack of thereof.
- Panu -
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