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Re: [help-a-newb] setting grub



On Thu, Apr 7, 2011 at 7:58 PM, Tom H <tomh0665@gmail.com> wrote:
> On Thu, Apr 7, 2011 at 3:02 AM, Joel Rees <joel.rees@gmail.com> wrote:
>> [...]
> F15's failure may or may not be grub's fault... F15's in alpha mode so
> it's most probably F15 but we can't tell from your posts.

Actually, it's looking like my new drive has hardware issues. I can't
believe they sell these things without even one selection strap these
days, so I have the master/slave selction flying in the breeze. I'll
have to bike over to the store tomorrow and shell out 280 yen for a
strap tomorrow, I guess.

(I know, the electronics are supposed to automatically select that for
you, but I just generally have problems with this
motherboard/controller set unless I strap those.)

> [...]
>> Manual is no problem here, because it would chain, and Fedora [takes]
>> care of its own grub.
>>
>> That's the whole point of chaining. Debian doesn't have to know how to
>> sift through Fedora or openBSD or openSolaris partitions or whatever.
>> Just chain to whatever boot loader is stored in the base partition
>> specified.
>>
>> Anyway, I have been playing with that. I found an example or two for
>> chaining to MSWindows which looked possible, but don't seem to work.
>>
>> I found a tutorial at
>> <http://www.dedoimedo.com/computers/grub-2.html>
>>
>> and [the] manual at
>>
>> <http://www.gnu.org/software/grub/manual/html_node/index.html#Top>
>>
>> [...]
>> I've made several stabs at this, but the present one ("09_fedora",
>> with the execution bit properly set) looks like this:
>>
>> ----------------------------
>> #! /bin/sh -e
>> echo "adding chain to hd(1,1) and hd(2,1)"
>>
>> cat << ENDOFOTHERS
>> menuentry "Fedora on /dev/sda1" {
>>        insmod part_msdos
>>        insmod ext2
>>        insmod chain
>>        set root='(hd1,msdos1)'
>>        chainloader (hd1,msdos1)+1
>> }
>>
>> menuentry "Fedora on /dev/sdf1" {
>>        insmod part_msdos
>>        insmod ext2
>>        insmod chain
>>        set root='(hd2,msdos1)'
>>        chainloader (hd2,msdos1)+1
>> }
>> ENDOFOTHERS
>> --------------------------------------
>>
>> [...]
>
> The grub2 developers decided that most people wouldn't want to set up
> chainloads and would want update-grub to add all the available
> installs to grub.cfg to be directly bootable.

That's kind of the way it looks, which is kind of shocking to me.

> There's possibly a case
> to add an option to "/etc/default/grub" to choose to have other
> detected OSs with chainloads...

If insmod chain would work, I don't know why that would be necessary.
I guess it would be closer to the legacy behavior.

Maybe I'll grab the source and add an option to revert back to legacy
grub behavior. (Like I have time for that.  :-/)

> You can update "/boot/grub/device.map" with grub-mkdevicemap.

Would that have some advantage over simply doing a re- grub-install ?

> Check that you've used the correct (hdX,msdosY) for Fedora with
> grub-probe and possibly use a "search ..." line after the "set
> root..." line (or just use a "search ..." line).

Well, near as I can tell, it matches what the mod-prober part puts out
for the drive,partition stuff.

> Renaming 30_os-prober's a good solution too, although it doesn't solve
> the BFO problem without some intervention form your side but nothing
> else does.

Short of moving Debian off the first drive. Although the tutorial I
linked to above suggests that grub2 doesn't like to be called from
legacy grub. :-(

Well, renaming the os-prober module will at least be faster than moving Debian.

I think I'll do that for now.

Thanks for thinking through this with me.

--
Joel Rees


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