Date: Sat, 24 Nov 2012 20:59:16 +0100 From: Damien Fleuriot <ml@my.gd> To: "Lucas B. Cohen" <lbc@bnrlabs.com> Cc: Ralf Mardorf <ralf.mardorf@rocketmail.com>, "freebsd-questions@freebsd.org" <freebsd-questions@freebsd.org> Subject: Re: Multi-boot Linux + FreeBSD Message-ID: <EB5A2676-FA63-4039-9082-83FDE7FC0805@my.gd> In-Reply-To: <50B0FF17.8050309@bnrlabs.com> References: <1353773206.4982.20.camel@q> <50B0FF17.8050309@bnrlabs.com>
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While no expert, I would advise against running the kernel directly.
The loader allows you to boot in single user which may come handy at times.
On 24 Nov 2012, at 18:08, "Lucas B. Cohen" <lbc@bnrlabs.com> wrote:
> Hi Ralf,
>=20
> On 2012.11.24 17:06, Ralf Mardorf wrote:
>> Perhaps later today I'll install 9.0 amd64. If possible I'll keep my
>> Linux GRUB legacy. Can I use my menu.lst [1] and add a chainloader or
>> something similar to boot FreeBSD from /dev/sda1?
> I don't know if GRUB v1 allows that, on a multiboot system I use GRUB 2
> to either load FreeBSD's loader(8) :
>=20
> menuentry "FreeBSD (Loader)" {
> insmod part_bsd
> set root=3D'hd0,msdos2,bsd1'
> echo "Loading FreeBSD loader"
> kfreebsd /boot/loader
> echo "Starting FreeBSD loader"
> }
>=20
> or to run its kernel directly, after having passed it optional device hint=
s:
>=20
> menuentry "FreeBSD (Direct Boot)" {
> insmod ufs2
> set root=3D'hd0,msdos2,bsd1'
> echo "Loading FreeBSD kernel"
> kfreebsd /boot/kernel/kernel
> echo "Loading FreeBSD environment"
> kfreebsd_loadenv /boot/device.hints
> set kfreebsd.vfs.root.mountfrom=3Dufs:/dev/ada0s2
> echo "Booting FreeBSD"
> }
>=20
> I'm not saying it's impossible, but I'm unable to chainload to the
> loader code on my system with this:
> menuentry "FreeBSD (Chainload)" {
> insmod chain
> set root=3D'hd0,msdos2'
> chainloader +1
> }
>=20
>=20
>=20
>> FWIW I made backups of my HDD's MBRs.
>> I wonder if the installer will overwrite the MBR?
> Always a good thing to have backups. =46rom what I've experienced and
> read, 9.0-RELEASE's installer is not always predictable in that regard,
> it's probably safer to assume it'll won't do what you want, and just
> restore your MBR after the installation, to go back to using GRUB for
> dual-booting.
>=20
> Here's the pitfall, though: the MBR also holds the partition table. So
> make a fresh backup after you've created/reorganized the primary
> partitions (slices) on your disk using a tool you're familiar with.
> (Logical partitions and BSD partitions are stored differently, so they
> will survive an MBR restore, provided it doesn't modify the primary
> partition they're contained in.)
>=20
>> I also would like to know, if there's a way to recover the partition
>> table, including a primary FreeBSD partition/slice, if this ever should
>> get broken and there should be no backup of the partition table be
>> available.
> The partition table is held alongside the MBR, in the first logical
> sector of your disk. Restoring one will restore the other.
> For extra safety, you can save the output of partitioning tools like
> fdisk or GNU parted expressed in sectors.
>=20
> Hope this helps,
>=20
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