On Fri, Jun 29, 2012 at 2:08 PM, Rich Freeman <rich0@gentoo.org> wrote:
> On Fri, Jun 29, 2012 at 12:11 PM, Mike Gilbert <floppym@gentoo.org> wrote:
>> As far as I can tell, grub:0 only half-way updates itself; there is a
>> large ewarn telling the user that they must take action to install the
>> new version in the MBR. This seems a bit broken to me.
>
> In what way. *As far as I can tell I haven't gotten a grub upgrade in
> the last 5-7 years. *Since it is built static on amd64 (or at least it
> was when I last installed it) nothing ever breaks. *Maybe if I changed
> my boot partition to a different filesystem it might have issues, but
> grub just strikes me as one of those aint-broke-don't-fix things.
>

Right. I was contradicting vapier's statement that grub:0
automatically updates itself. It doesn't.

It does copy all of the images to /boot so that the grub shell can be
used to install an MBR image. grub:2 no longer has an interactive
shell and grub2-install must be used. Therefore, copying files to
/boot in the ebuild is completely pointless.

On Fri, Jun 29, 2012 at 2:29 PM, Mike Gilbert <floppym@gentoo.org> wrote:
> It does copy all of the images to /boot so that the grub shell can be
> used to install an MBR image. grub:2 no longer has an interactive
> shell and grub2-install must be used. Therefore, copying files to
> /boot in the ebuild is completely pointless.

Does grub2-install place any stage files where they need to be, or are
they no longer needed? I haven't experimented with it yet.

Normally grub1 needs to be able to find the stage2 file, and that has
to be on a partition the stage1.5 can read (I believe stage1.5 is in
the diagnostic cylinder - it only uses the files in /boot during
installation).

I'm not sure if grub2 completely eliminates the need to have a
"normal" partition somewhere, in a situation where raid+lvm+etc are
used.

Rich

On 06/29/2012 02:38 PM, Rich Freeman wrote:
> On Fri, Jun 29, 2012 at 2:29 PM, Mike Gilbert <floppym@gentoo.org> wrote:
>> It does copy all of the images to /boot so that the grub shell can be
>> used to install an MBR image. grub:2 no longer has an interactive
>> shell and grub2-install must be used. Therefore, copying files to
>> /boot in the ebuild is completely pointless.
>
> Does grub2-install place any stage files where they need to be, or are
> they no longer needed? I haven't experimented with it yet.
>
> Normally grub1 needs to be able to find the stage2 file, and that has
> to be on a partition the stage1.5 can read (I believe stage1.5 is in
> the diagnostic cylinder - it only uses the files in /boot during
> installation).
>
> I'm not sure if grub2 completely eliminates the need to have a
> "normal" partition somewhere, in a situation where raid+lvm+etc are
> used.
>
> Rich
>

GRUB2 does away with the conventional stage files. It also wants a
special BIOS Boot Partition in order to function. That is where it
stores the equivalent of the stage2 bootcode. That is similar to
FreeBSD's bootloader.

On Fri, Jun 29, 2012 at 2:51 PM, Richard Yao <ryao@gentoo.org> wrote:
> GRUB2 does away with the conventional stage files. It also wants a
> special BIOS Boot Partition in order to function. That is where it
> stores the equivalent of the stage2 bootcode. That is similar to
> FreeBSD's bootloader.

Now, that should make for a fun migration! Fortunately I do have a
separate boot already, and I guess I can be daring and overwrite it in
place and trust in grub2 to still find the kernel elsewhere.

Those without a separate boot and without any free space are likely to
find this to be painful. Resizing partitions isn't exactly
risk-free...

Rich

On Fri, Jun 29, 2012 at 2:38 PM, Rich Freeman <rich0@gentoo.org> wrote:
> On Fri, Jun 29, 2012 at 2:29 PM, Mike Gilbert <floppym@gentoo.org> wrote:
>> It does copy all of the images to /boot so that the grub shell can be
>> used to install an MBR image. grub:2 no longer has an interactive
>> shell and grub2-install must be used. Therefore, copying files to
>> /boot in the ebuild is completely pointless.
>
> Does grub2-install place any stage files where they need to be, or are
> they no longer needed? *I haven't experimented with it yet.
>
> Normally grub1 needs to be able to find the stage2 file, and that has
> to be on a partition the stage1.5 can read (I believe stage1.5 is in
> the diagnostic cylinder - it only uses the files in /boot during
> installation).

grub2 eliminates the stage_1_5 files. Instead, a "core" image is built
by grub2-install.

Here's how it works.

1. grub2-install copies all grub modules to /boot/grub2. This can be
any file system readable by GRUB.
2. grub2-install calls grub2-mkimage which combines any modules
necessary to access /boot into core.img.
3. grub2-install calls grub2-bios-setup which installs boot.img into
the MBR and embeds core.img into the sectors immediately after the
MBR.

>
> I'm not sure if grub2 completely eliminates the need to have a
> "normal" partition somewhere, in a situation where raid+lvm+etc are
> used.

You do need a filesystem that grub2 can access through some
combination of modules, and an area in which to embed core.img.

The grub2 manual has a pretty good explanation.

http://www.gnu.org/software/grub/manual/html_node/Installing-GRUB-using-grub_002dinstall.html
http://www.gnu.org/software/grub/manual/html_node/BIOS-installation.html
http://www.gnu.org/software/grub/manual/html_node/Images.html

On Fri, Jun 29, 2012 at 3:00 PM, Rich Freeman <rich0@gentoo.org> wrote:
> On Fri, Jun 29, 2012 at 2:51 PM, Richard Yao <ryao@gentoo.org> wrote:
>> GRUB2 does away with the conventional stage files. It also wants a
>> special BIOS Boot Partition in order to function. That is where it
>> stores the equivalent of the stage2 bootcode. That is similar to
>> FreeBSD's bootloader.
>
> Now, that should make for a fun migration! *Fortunately I do have a
> separate boot already, and I guess I can be daring and overwrite it in
> place and trust in grub2 to still find the kernel elsewhere.
>
> Those without a separate boot and without any free space are likely to
> find this to be painful. *Resizing partitions isn't exactly
> risk-free...
>
> Rich
>

I think Richard is incorrect here; grub2 can live on any filesystem,
so long as some combination of modules can access it.

On Fri, Jun 29, 2012 at 3:01 PM, Mike Gilbert <floppym@gentoo.org> wrote:
> 3. grub2-install calls grub2-bios-setup which installs boot.img into
> the MBR and embeds core.img into the sectors immediately after the
> MBR.

Ok, that isn't all that unlike grub1 - that is what stage1.5 is. It
just sounds like these aren't static files that are copied out of
/boot/grub, but rather they're built on-demand from other files there.
Grub1 figures out which static stage1.5 you need based on where /boot
is. They probably went to a more dynamic model so that they can
support stuff like LVM+MD+LUKS+etc without having every permutation of
static code. I'm not sure how smart the bootloader code ends up being
- it wouldn't surprise me if at time of install the installer does all
the work and just loads a simple bootloader on the diagnostic cylinder
with just enough smarts to find /boot if it hasn't changed.

Rich

On Fri, Jun 29, 2012 at 3:15 PM, Rich Freeman <rich0@gentoo.org> wrote:
> On Fri, Jun 29, 2012 at 3:01 PM, Mike Gilbert <floppym@gentoo.org> wrote:
>> 3. grub2-install calls grub2-bios-setup which installs boot.img into
>> the MBR and embeds core.img into the sectors immediately after the
>> MBR.
>
> Ok, that isn't all that unlike grub1 - that is what stage1.5 is. *It
> just sounds like these aren't static files that are copied out of
> /boot/grub, but rather they're built on-demand from other files there.
> *Grub1 figures out which static stage1.5 you need based on where /boot
> is. *They probably went to a more dynamic model so that they can
> support stuff like LVM+MD+LUKS+etc without having every permutation of
> static code. *I'm not sure how smart the bootloader code ends up being
> - it wouldn't surprise me if at time of install the installer does all
> the work and just loads a simple bootloader on the diagnostic cylinder
> with just enough smarts to find /boot if it hasn't changed.

Spot on. :-)

On 06/29/2012 03:04 PM, Mike Gilbert wrote:
> On Fri, Jun 29, 2012 at 3:00 PM, Rich Freeman <rich0@gentoo.org> wrote:
>> On Fri, Jun 29, 2012 at 2:51 PM, Richard Yao <ryao@gentoo.org> wrote:
>>> GRUB2 does away with the conventional stage files. It also wants a
>>> special BIOS Boot Partition in order to function. That is where it
>>> stores the equivalent of the stage2 bootcode. That is similar to
>>> FreeBSD's bootloader.
>>
>> Now, that should make for a fun migration! Fortunately I do have a
>> separate boot already, and I guess I can be daring and overwrite it in
>> place and trust in grub2 to still find the kernel elsewhere.
>>
>> Those without a separate boot and without any free space are likely to
>> find this to be painful. Resizing partitions isn't exactly
>> risk-free...
>>
>> Rich
>>
>
> I think Richard is incorrect here; grub2 can live on any filesystem,
> so long as some combination of modules can access it.
>

Do you know what function the BIOS Boot Partion serves? It is necessary
when using GRUB2's ZFS support. I was under the impression that it
stored boot code.

On Fri, Jun 29, 2012 at 4:56 PM, Richard Yao <ryao@gentoo.org> wrote:
> On 06/29/2012 03:04 PM, Mike Gilbert wrote:
>> On Fri, Jun 29, 2012 at 3:00 PM, Rich Freeman <rich0@gentoo.org> wrote:
>>> On Fri, Jun 29, 2012 at 2:51 PM, Richard Yao <ryao@gentoo.org> wrote:
>>>> GRUB2 does away with the conventional stage files. It also wants a
>>>> special BIOS Boot Partition in order to function. That is where it
>>>> stores the equivalent of the stage2 bootcode. That is similar to
>>>> FreeBSD's bootloader.
>>>
>>> Now, that should make for a fun migration! *Fortunately I do have a
>>> separate boot already, and I guess I can be daring and overwrite it in
>>> place and trust in grub2 to still find the kernel elsewhere.
>>>
>>> Those without a separate boot and without any free space are likely to
>>> find this to be painful. *Resizing partitions isn't exactly
>>> risk-free...
>>>
>>> Rich
>>>
>>
>> I think Richard is incorrect here; grub2 can live on any filesystem,
>> so long as some combination of modules can access it.
>>
>
> Do you know what function the BIOS Boot Partion serves? It is necessary
> when using GRUB2's ZFS support. I was under the impression that it
> stored boot code.
>

Based on a Google search I think "BIOS Boot Partition" is a GPT thing.
Not relevent if you have an MBR partition table.