grub nilfs2 module

Hi,

I've written nilfs2 module for grub2 boot loader.

Here is the patch and mail I'v sent to grub-devel ML.
http://lists.gnu.org/archive/html/grub-devel/2010-02/msg00025.html

It may not be mature yet, but I was able to boot kernel from nilfs2 partition and mount it as rootfs.
So you are able to boot the system that has only nilfs2 partition.

The patch is against bazaar repository top, but actual code is just a fs/nilfs2.c. Other patches are against makefiles. So I think you can able to compile it in stable release with slight modification.

It would be very nice of you if you try and give me feed backs to improve the module.

thank you very much in advance!

Signature · 5 lines

Jiro SEKIBA <[email protected]>
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Hi,

Quoted 6 lines · Jiro SEKIBA

Hi,

I've written nilfs2 module for grub2 boot loader.

Here is the patch and mail I'v sent to grub-devel ML.
http://lists.gnu.org/archive/html/grub-devel/2010-02/msg00025.html

Great!

The patch looks fine to me except some work, for instance, rollforwarding and checksum based log validation is needed.

But meanwhile, this prototype seems enough to load kernels and initrds.

I'd like to try it for my laptop.

Quoted 3 lines

It may not be mature yet, but I was able to boot kernel from nilfs2 partition and mount it as rootfs.
So you are able to boot the system that has only nilfs2 partition.

Hi,

Quoted 11 lines · Ryusuke Konishi

Hi,

Quoted 6 lines · Jiro SEKIBA

Hi,

I've written nilfs2 module for grub2 boot loader.

Here is the patch and mail I'v sent to grub-devel ML.
http://lists.gnu.org/archive/html/grub-devel/2010-02/msg00025.html

Great!

Quoted 11 lines

The patch looks fine to me except some work, for instance, rollforwarding and checksum based log validation is needed.

But meanwhile, this prototype seems enough to load kernels and initrds.

I'd like to try it for my laptop.

Quoted 3 lines

It may not be mature yet, but I was able to boot kernel from nilfs2 partition and mount it as rootfs.
So you are able to boot the system that has only nilfs2 partition.

Let me ask you a question.

One thing which is important in NILFS is that every block in the partition can be moved by the garbage collection (except two super blocks).

So, we cannot assume that file blocks stay in a locked position even for unmodified files.

Doesn't this cause problems for the boot sequence of GRUB2 ?

Regards,
Ryusuke Konishi
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Hi,

At Thu, 04 Feb 2010 16:54:56 +0900 (JST),

Quoted 28 lines · Ryusuke Konishi

Hi,

Quoted 11 lines · Ryusuke Konishi

Hi,

Quoted 6 lines · Jiro SEKIBA

Hi,

I've written nilfs2 module for grub2 boot loader.

Here is the patch and mail I'v sent to grub-devel ML.
http://lists.gnu.org/archive/html/grub-devel/2010-02/msg00025.html

Great!

Quoted 11 lines

The patch looks fine to me except some work, for instance, rollforwarding and checksum based log validation is needed.

But meanwhile, this prototype seems enough to load kernels and initrds.

I'd like to try it for my laptop.

Quoted 3 lines

It may not be mature yet, but I was able to boot kernel from nilfs2 partition and mount it as rootfs.
So you are able to boot the system that has only nilfs2 partition.

Let me ask you a question.

Quoted 8 lines

One thing which is important in NILFS is that every block in the partition can be moved by the garbage collection (except two super blocks).

So, we cannot assume that file blocks stay in a locked position even for unmodified files.

Doesn't this cause problems for the boot sequence of GRUB2 ?

That's a good question.

It's basically OK because there usually are room for additional code besides MBR in PC disk format. The room size is 32KiB followed by MBR. The room is not required for linux, but historically for DOS compat.

See the link how modern disk layout is.
http://www.pixelbeat.org/docs/disk/

You can check it with the dd by following

# dd if=/dev/hda of=hda bs=512 count=3 skip=65
# hexdump -C hda > hda.hex
# dd if=/dev/hda1 of=hda1 bs=512 count=3
# hexdump -C hda1 > hda1.hex

NOTE, the differences between two dumps are, I think, mtime in a super block.

So if you install grub2 with root directory in nilfs2, grub-install will install nilfs2.mod into that additional 32KiB space The space is out of nilfs2 patition, so GC won't move the blocks.

thanks

It would be nice if you could tell us belief usage of the patch.

Hi,

Quoted 1 line

It would be nice if you could tell us belief usage of the patch.

OK, sure. It's against bazaar repository, so you have to build it from repository source instead of latest stable release tarball.

To build with stable release(1.97.2), you need to modify fs/nilfs2.c not to use grub_xasprintf, but use grub_malloc and grub_sprintf.

You may get reject for makefile, but I think it'll be OK.

Here are the instruction to retrieve grub repository and build the softoware.

$ bzr branch http://bzr.savannah.gnu.org/r/grub/trunk/grub
$ cd grub
$ patch -p0 < /path/to/the/patch
$ sh autogen.sh
$ ./configure
$ make

you need "make install" as usual. It will install under /usr/local without giving any parameters for ./configure.

The "make install" won't install grub to MBR.
To install grub into MBR, you have to "grub-install" to target disk.

For example, assume that you have nilfs2 filesystem on hdb1, mounted on /mnt and want to enable hdb as bootable. You'll do

# grub-install --root-directory=/mnt /dev/hdb

This will install grub into hdb's MBR and other required files into following 32KiB blocks. Fuhtermore, it'll install files under /mnt/boot/grub. Those files are not required to boot grub to read the filesystem.

hdb is now self bootable disk. You'll just connect it as hdb and grub will boot up.

Note, during grub-install, /boog/grub/grub.cfg will be copied int to /mnt/boo/grub, which is not the one for hdb. So you have edit menu at first time you boot with hdb. After boot the system, you can reproduce the menu by grub-mkcofnig > /boot/grub/grub.cfg

Enjoy!

Quoted 42 lines

OK, sure. It's against bazaar repository, so you have to build it from repository source instead of latest stable release tarball.

To build with stable release(1.97.2), you need to modify fs/nilfs2.c not to use grub_xasprintf, but use grub_malloc and grub_sprintf.

You may get reject for makefile, but I think it'll be OK.

Here are the instruction to retrieve grub repository and build the softoware.

$ bzr branch http://bzr.savannah.gnu.org/r/grub/trunk/grub
$ cd grub
$ patch -p0 < /path/to/the/patch
$ sh autogen.sh
$ ./configure
$ make

you need "make install" as usual. It will install under /usr/local without giving any parameters for ./configure.

The "make install" won't install grub to MBR.
To install grub into MBR, you have to "grub-install" to target disk.

For example, assume that you have nilfs2 filesystem on hdb1, mounted on /mnt and want to enable hdb as bootable. You'll do

# grub-install --root-directory=/mnt /dev/hdb

This will install grub into hdb's MBR and other required files into following 32KiB blocks. Fuhtermore, it'll install files under /mnt/boot/grub. Those files are not required to boot grub to read the filesystem.

hdb is now self bootable disk. You'll just connect it as hdb and grub will boot up.

Note, during grub-install, /boog/grub/grub.cfg will be copied int to /mnt/boo/grub, which is not the one for hdb. So you have edit menu at first time you boot with hdb. After boot the system, you can reproduce the menu by grub-mkcofnig > /boot/grub/grub.cfg

Quoted 1 line

Enjoy!

Thank you once again.

I'll catch up the above steps and then comment later.

Ryusuke