[SOLVED]Need to modify /etc/default/grub before 1st boot

[big-red-cow]

I'm installing linuxmint 20.1 xfce to an Acer Chromebook 11 C740. When booting from the live USB, I must first edit the boot parameters for Casper by adding the line i915.fastboot=1, otherwise the screen flashes on and off constantly.

Also, during the install, I need to keep the display active, so I install xscreensaver and set for random screensavers after 1 minute.

All is well, I get the release installed, but after rebooting, there is no way for me to intercept grub and modify the boot parameters prior to getting into the system and adjusting /etc/default/grub and then running update-grub.

Pressing the "normal" keys doesn't help me: I can press Esc or Right-Shift, and the bootup may pause, but I never get into the grub edit.

I realize this is likely a quirk of my Chromebook, as it's not using UEFI unless I'm willing to remove the write-protect and flash the bios.

If I were clever enough, I would chroot into the freshly installed system and fix it myself while I'm still in the live usb. But I'm not quite there yet.

Any ideas?

[spamegg]

By holding Shift, you can go into Advanced Options/Recovery Mode, then "drop to root shell" and you can use a command-line editor like nano to edit /etc/default/grub and update-grub.

But you shouldn't have to do all this stuff you are doing. There must be some other solution, some alternative to the i915.fastboot=1 trick.

[rene]

He said he can't get into the Grub menu...

Does it have a regular SATA drive? If so and if it's /dev/sda and your newly installed rootfs is on /dev/sda1 with /boot not split off and, seemingly, in your case no separate EFI system partition on /boot/efi, from a terminal on the Live USB post-install

Code: Select all

$ sudo -s
# mount /dev/sda1 /mnt
# vi /mnt/etc/default/grub 
# mount --bind /dev /mnt/dev
# mount --bind /sys /mnt/sys
# mount --bind /proc /mnt/proc
# chroot /mnt update-grub
# exit
$

Feel free of course to use e.g. nano rather than vi if you like.

[rene]

Oh, wait. But he also said explicitly Right-Shift and it in fact needs to be specifically Left-Shift at least on normal legacy systems.

[spamegg]

Right, it should be Left Shift.

I understood that he could not get into Grub-edit, not Grub. I guess I don't get it.

[big-red-cow]

By holding Shift, you can go into Advanced Options/Recovery Mode, then "drop to root shell" and you can use a command-line editor like nano to edit /etc/default/grub and update-grub.

But you shouldn't have to do all this stuff you are doing. There must be some other solution, some alternative to the i915.fastboot=1 trick.

nomodeset is the typical way around incompatible video cards or situations, but this yields a very slow system with the wrong screen dimensions. i915 works great, once I get grub setup. Thanks for your reply.

[rene]

Have you done the above to edit post-install from the live system?

[rene]

I understood that he could not get into Grub-edit, not Grub. I guess I don't get it.

There is no such thing as boot-time "Grub-edit" other than edting the Grub commands from the Grub menu; the same menu you'd pick those 'Advanced Options' from.

[big-red-cow]

He said he can't get into the Grub menu...

Does it have a regular SATA drive? If so and if it's /dev/sda and your newly installed rootfs is on /dev/sda1 with /boot not split off and, seemingly, in your case no separate EFI system partition on /boot/efi, from a terminal on the Live USB post-install

Code: Select all

$ sudo -s
# mount /dev/sda1 /mnt
# vi /mnt/etc/default/grub 
# mount --bind /dev /mnt/dev
# mount --bind /sys /mnt/sys
# mount --bind /proc /mnt/proc
# chroot /mnt update-grub
# exit
$

Feel free of course to use e.g. nano rather than vi if you like.

This is exactly what I was looking for! I had to wait until after I chrooted to modify /etc/default/grub, because the changes I made were not getting saved. This is the simplest explanation for using chroot into an existing system. Thank you so much!

[big-red-cow]

Have you done the above to edit post-install from the live system?

Yes! Thanks for asking.

[rene]

I had to wait until after I chrooted to modify /etc/default/grub, because the changes I made were not getting saved.

I expect you didn't before the chroot say /mnt/etc/default/grub rather than just /etc/default/grub then. But in any case good that it worked; I followed up due to being momentarily "scared" that my own next "Oh, wait" post was taken literally to mean that the chroot advise wouldn't work.

[big-red-cow]

I had to wait until after I chrooted to modify /etc/default/grub, because the changes I made were not getting saved.

I expect you didn't before the chroot say /mnt/etc/default/grub rather than just /etc/default/grub then. But in any case good that it worked; I followed up due to being momentarily "scared" that my own next "Oh, wait" post was taken literally to mean that the chroot advise wouldn't work.

Duhhh... Yeah, you are correct. I'm pretty sure I left off the /mnt.

No key works at the grub menu: Left-Shift, Right-Shift, or Esc: to stop the boot on my quirky little Chromebook.

Most distros I've seen set the timeout to zero, and the timeout style to hidden, so there is no way I could have solved this without your chroot advice. I've printed this out and saved it in a Linux notebook I keep. Thanks, I can't wait to play around with this idea some more.