Re: Boot loaders for Linux that can also boot FreeBSD

[Tom H <tomh0665@gmail.com>]

On Thu, Nov 29, 2012 at 8:58 AM, Ralf Mardorf
<ralf.mardorf@alice-dsl.net> wrote:
>
> I need a boot loader for Linux, that is comfortable to use for my needs,
> a Linux multi-boot with
> trillions of Linux installs,
> trillions ^ 2 kernels and
> (trillions ^ 2) * 1024 entries with different boot options, so something
> as GRUB 2 is unusable for my needs.
>
> Until now I was comfortable with GRUB legacy, but now I add a FreeBSD
> install to my machine and against the claims at
>
> http://en.wikipedia.org/wiki/Comparison_of_boot_loaders
>
> GRUB legacy does not boot FreeBSD (until now). I was thinking of
> SYSLINUX, perhaps the most popular bootloader by Linux experts, but the
> Wiki says it doesn't support booting BSD.
>
> Since access to the freebsd-ufs partition by Linux is a PITA and Linux
> is most important for me, I wont use a FreeBSD bootloader. I need easy
> access to the bootloader's configuration file.
>
> On a FreeBSD mailing list somebody wrote:
>>
>> You might want to try a chainloader boot from grub. The following is a
>> chainloader rule that I have used, as well as a normal loader boot. I
>> use the loader boot, but I also tested the chainloader boot. You will
>> need a ufs2_stage1_5 file in your grub directory for a loader boot, and
>> linux grub might not have it available.
>>
>> title           FreeBSD, sda3 (oak) chainloader
>> root            (hd1,2)
>> chainloader     +1
>> boot
>>
>> title           FreeBSD, sda3 (oak) /boot/loader
>> root            (hd1,2,a)
>> kernel          /boot/loader
>> boot
>
> Yes, ufs2_stage1_5 is missing, so when I tested
>
> #title FreeBSD
> #root   (hd0,a)
> #kernel /boot/loader
>
> title FreeBSD
> rootnoverify (hd0,1)
> chainloader +1
> boot
>
> there was no error, but nothing happened, without the chainloader an
> error 17, cannot mount selected partition appeared.

I'm sure that I'm going to regret asking however here goes: why is
grub2 unsuitable?

With grub2:

1) Multiboot from [a]:

menuentry "FreeBSD" {
	insmod zfs
	search --set=root --label freepool --hint hd0,msdos7
	kfreebsd /freebsd@/boot/kernel/kernel
	kfreebsd_module_elf /freebsd@/boot/kernel/opensolaris.ko
	kfreebsd_module_elf /freebsd@/boot/kernel/zfs.ko
	kfreebsd_module /freebsd@/boot/zfs/zpool.cache type=/boot/zfs/zpool.cache
	set kFreeBSD.vfs.root.mountfrom=zfs:freepool/freebsd
	set kFreeBSD.hw.psm.synaptics_support=1
}

2) Multiboot from notes that I saved:

(get the uuid of the bsd boot slice with grub-probe)

menuentry "FreeBSD" {
	insmod part_msdos
	insmod part_bsd
	insmod ufs2
	search --no-floppy --set=root --fs-uuid <uuid>
	kfreebsd /boot/kernel/kernel
	kfreebsd_loadenv /boot/device.hints
	set FreeBSD.vfs.root.mountfrom=ufs:ufsid/<uuid>
	set FreeBSD.vfs.root.mountfrom.options=rw
}

You can also use "set FreeBSD.vfs.root.mountfrom=ufs:/dev/adXsYZ"

2) Chainload

(get the uuid of the bsd boot slice with grub-probe)

menuentry "FreeBSD" {
	insmod part_msdos
	insmod part_bsd
	insmod ufs2
	search --no-floppy --set=root --fs-uuid <uuid>
	kfreebsd /boot/loader
}

menuentry "FreeBSD" {
	insmod part_msdos
	insmod part_bsd
	insmod ufs2
	search --no-floppy --set=root --fs-uuid <uuid>
	chainloader +1
}

a. http://www.gnu.org/software/grub/manual/html_node/Multi_002dboot-manual-config.html#Multi_002dboot-manual-config