Arch Linux

nourathar

Member

From: Bxl

Registered: 2013-04-26

Posts: 112

[Solved] os-prober can't find second Arch install

Hi,

on my laptop I have a triple boot setup with:

- an Arch install with lots of bells and whistles
- a windows7 version I never use but which I keep just in case
- an Arch install that I keep as small and clean as possible

I always maintain grub from the first install on that list and until now os-prober nicely detected both the Windows loader and the second Arch install.
Since the 23 june update or move of core/grub that no longer works: if I run grub-mkconfig it sees the Windows loader but not the second Arch install. I've been reading on the Wiki and I installed lsb-release (without knowing what that is but it was mentioned that it improved detection of Arch in some cases), but that did not make difference.

Any ideas how I can get my second Arch back in the grub menu ?
What causes this and how can I prevent this from happening again  ?

many thanks,

J.

Last edited by nourathar (2013-06-25 13:50:39)

henk

Member

From: Weert, Netherlands

Registered: 2013-01-01

Posts: 334

Re: [Solved] os-prober can't find second Arch install

As for the first question, mount the partition that contains your second Arch install under /mnt, en run grub-mkconfig once again.
As for the second question, I really don't know.
Question: why did you run grub-mkconfig after the update? From the pacman -log:

[PACMAN] removed grub-bios (2.00-2)
[ALPM] warning: /boot/grub/grub.cfg saved as /boot/grub/grub.cfg.pacsave
[PACMAN] removed grub-common (2.00-2)
[ALPM-SCRIPTLET] Copying /boot/grub/grub.cfg.pacsave to /boot/grub/grub.cfg
[ALPM-SCRIPTLET] Generating grub.cfg.example config file...

your existing grub.cfg still would work.

nourathar

Member

From: Bxl

Registered: 2013-04-26

Posts: 112

Re: [Solved] os-prober can't find second Arch install

Thanks for the reply: mounting makes a difference in that it says it found the second Arch, but strangely enough it does not actually make a menu-entry.
If I run grub-mkconfig without specifying the outputfile (so that I see what it generates), the os-prober block is as follows:

### BEGIN /etc/grub.d/30_os-prober ###
  No volume groups found
Found Windows 7 (loader) on /dev/sda2
menuentry 'Windows 7 (loader) (on /dev/sda2)' --class windows --class os $menuentry_id_option 'osprober-chain-5C305B85305B64D4' {
        insmod part_msdos
        insmod ntfs
        set root='hd0,msdos2'
        if [ x$feature_platform_search_hint = xy ]; then
          search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos2 --hint-efi=hd0,msdos2 --hint-baremetal=ahci0,msdos2  5C305B85305B64D4
        else
          search --no-floppy --fs-uuid --set=root 5C305B85305B64D4
        fi
        chainloader +1
}
Found Arch on /dev/sda6

### END /etc/grub.d/30_os-prober ###

What is going on ? How can it find my second install and not do anything ?

And as for your last question; I have no idea ? Perhaps not very clever indeed, but when reading the pacman log I was somehow under the impression that would be a safe and wise thing to do, and I certainly didn't expect behaviour that was different from the very painless previous time I did this...

thanks,

J.

Last edited by nourathar (2013-06-24 16:39:39)

henk

Member

From: Weert, Netherlands

Registered: 2013-01-01

Posts: 334

Re: [Solved] os-prober can't find second Arch install

As a workaround you could use grub-customizer
https://aur.archlinux.org/packages/grub-customizer
to make a custom entry for your second Arch-install; I used it in Xubuntu where grub didn't find the Arch installs either.
-install grub-customizer
-mount /dev/sda6 to /mnt
-start grub-customizer
If your second arch install is listed edit it. This way it becomes a custom entry
Save, and save it to the MBR

nourathar

Member

From: Bxl

Registered: 2013-04-26

Posts: 112

Re: [Solved] os-prober can't find second Arch install

aha, thanks/dankjewel, I'm going to try that !

nourathar

Member

From: Bxl

Registered: 2013-04-26

Posts: 112

Re: [Solved] os-prober can't find second Arch install

Thanks a lot, that worked like a charm !

andrekp

Member

Registered: 2012-06-07

Posts: 112

Re: [Solved] os-prober can't find second Arch install

I know this post is a couple days old and supposedly solved but:

As a suggestion, if anyone's still looking, this is exactly a situation where you don't need to be generating new menus every time at all.  Just make one that works, put the details in the grub.d custom file entry, and let grub do what it wants.  neither Arch nor Wndows will ever need an updated grub entry really, so running update-grub and making the os-prober go looking, in your case, is just asking for problems like this.

I was a lot happier once I realized and accepted this myself.

In case you aren't sure, do some research on grub and making custom menu entries.  Eventually, you'll see what I mean if you don't yet.  Grub customizer is not really the answer in this case.

(But note that grub customizer screws with your standard grub files, so you may need to find a fresh set of them to get everything correct again.  Grub customizer is sort of a trapdoor.)

Last edited by andrekp (2013-06-28 17:43:53)