[SOLVED]Can os-prober detect windows prior grub writing EFI partition?

robster · 2016-03-07 02:43:46

I did a Grub based installation for the first time yesterday. Putting Arch on a second HDD, and dual booting Windows 10. Os-prober failed to detect Windows 10 prior to writing to the EFI partition on the first HDD, so i wiote back the windows boot manager, then ran grub mkconfig again so os-probe would pick up the windows boot manager I had written back to the efi boot partition. Grub threw out some spurious errors, but the installation was successful.

My question: Is it possible to rewrite the grub routines so they use os-prober prior to writing to any boot partitions?

This would make dual booting from anywhere an easier proposition and alleviate all those forum entries "I can't start windows", that seem to proliferate in any disto's forum where manual installation of grub is required and some where the automatic installation of grub hasn't considered all possibilities.

Last edited by robster (2016-03-09 03:53:04)

Strike0 · 2016-03-08 12:32:09

Making a "universal" os-probe routine is an idea, but tricky. Grub already features tools like grub-probe, then there is the os-prober you mention.

robster wrote:

..so i wiote back the windows boot manager, then ran grub mkconfig again so os-probe would pick up the windows boot manager I had written back to the efi boot partition. Grub threw out some spurious errors, but the installation was successful.

Not sure what you mean with "wrote back the windows boot manager". The original one was not deleted by an install routine, was it?

Apart from that: your idea is unlikely to be implemented by Arch, even if you open a bug report for it. There are so many different windows versions and hardware quirks for UEFI etc, e.g. see https://wiki.archlinux.org/index.php/Du … imitations
(some of which (windows fast start-up) even corrupt boot signatures when not disabled in windows). The wiki also lists some approaches for grub: https://wiki.archlinux.org/index.php/GRUB#Dual-booting
Once you configure your custom grub configuration file according to what your system partitions feature, grub-mkconfig should do its task fine.

robster · 2016-03-08 14:24:28

Thanks for the reply @Strike0

Strike0 wrote:

The original one was not deleted by an install routine, was it?.

Yes it was, Grub did what it was instructed, I expected it to probe for Windows 10, and be able to happily coincide with the Windows 10 boot manager. It didn't find Windows 10 boot manager, overwrote it. I then manually reinserted the Windows 10 bootmanager into the same EFI partition as grub. Now they both occupy the same EFI partition. I reran mkconfig, Grub made the relevant boot menu entry.

Should mention I installed Arch on the third partition of my 2nd HDD, and was using the EFI partition on the 1st HDD.

But anyway the system is happily dual booting, it just took me an extra step.

Trilby · 2016-03-08 15:07:03

Robster would you please edit your first post and give this thread a meaninful title. Grub is possible - your question seems to related getting os-prober (or some such tool) to detect windows boot loaders (I think). That should be in the title to attract the attention of people with the relevant experience.

EDIT: thanks - this is a much better title.

Strike0 · 2016-03-08 18:44:58

robster wrote:

Yes it was, Grub did what it was instructed, I expected it to probe for Windows 10, and be able to happily coincide with the Windows 10 boot manager. It didn't find Windows 10 boot manager, overwrote it. I then manually reinserted the Windows 10 bootmanager into the same EFI partition as grub. Now they both occupy the same EFI partition. I reran mkconfig, Grub made the relevant boot menu entry.
Should mention I installed Arch on the third partition of my 2nd HDD, and was using the EFI partition on the 1st HDD.

The system partition does not matter, only one EFI partition is what counts and that was the case.

What I still don't know why it overwrote anything, the grub efistub has a different name. But anyway, looking at the grub package, os-prober is just an _optional_ dependency. So it is not installed automatically when you install the grub package. Did you perhaps install os-prober _after_ the first attempt (i.e. before rerunning the grub-install/configuration)? Then it would be logical to me that it did not detect the windows efi file at the first attempt. If this is the case, it could (possibly - depending on evaluation of the package maintainer) be changed if you open a bug report and request os-prober being a required (not optional) dependency.

robster · 2016-03-09 03:49:12

@Strike0,
I'm beginning to question my sanity :-) Considering what you have explained, I must consider one other alternative, and for the life of me I don't know why I would have done it, but the possibility must be considered, that I formatted the EFI partition during the install. I can't remember doing it, but it would explain what happened. (Have a bad habit of working until the keyboard is imprinted on my forehead.)

As to os-prober--it was installed prior to first attempt.

I'm going to put Solved on this, as I don't intend trying to replicate the process and I'm beginning to question my own actions.

Thank you for your time and patience.

Strike0 · 2016-03-09 07:16:50

One way to figure out what happened would be to look at the directories/files on the EFI partition and their creation time. If the folder for the Microsoft boot (likely the EFI partition contains other folders too, e.g. from the hardware vendor) have the same or later timestamp as the Linux folders/first attempt, it would explain you restored them after the first attempt. If they are earlier, you did not do that.

But anyway - it works/boots, whatever happened. Have fun!

Arch Linux

#1 2016-03-07 02:43:46

[SOLVED]Can os-prober detect windows prior grub writing EFI partition?

#2 2016-03-08 12:32:09

Re: [SOLVED]Can os-prober detect windows prior grub writing EFI partition?

#3 2016-03-08 14:24:28

Re: [SOLVED]Can os-prober detect windows prior grub writing EFI partition?

#4 2016-03-08 15:07:03

Re: [SOLVED]Can os-prober detect windows prior grub writing EFI partition?

#5 2016-03-08 18:44:58

Re: [SOLVED]Can os-prober detect windows prior grub writing EFI partition?

#6 2016-03-09 03:49:12

Re: [SOLVED]Can os-prober detect windows prior grub writing EFI partition?

#7 2016-03-09 07:16:50

Re: [SOLVED]Can os-prober detect windows prior grub writing EFI partition?

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