Date: Thu, 22 Aug 2013 02:41:06 +0000 From: "Thomas Mueller" <mueller6724@bellsouth.net> To: freebsd-stable@freebsd.org Cc: "Andrey V. Elsukov" <ae@FreeBSD.org>, Juergen Lock <nox@FreeBSD.ORG> Subject: Re: Change in loader or kernel: won't boot with kfreebsd in grub2 Message-ID: <FA.55.18705.24A75125@hrndva-omtalb.mail.rr.com>
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> Not sure about a physical cd but booting an iso should be possible
> using either memdisk from grub2 like in the posting I linked,
> http://ubuntuforums.org/showthread.php?t=1549847&page=13&p=10818457#post10818457
> _or_ also using grub2's own loopback command like described here:
> http://michael-prokop.at/blog/2009/05/25/boot-an-iso-via-grub2/
> (but btw the super grub disk iso should also boot directly when dd'd
> to an usb key, not only when burned to a cd/dvd.)
> It could only be that the partition table on your disk is somehow
> messed up/has leftover data from a previous install that confused
> loader and might confuse grub2 too so that it doesn't find the
> FreeBSD install...
> > I also wonder how or if one can boot a FreeBSD partition from GRUB2 or syslinux.
>
> That's what super grub disk's autodetection should now detect
> correctly, if you want to write a grub.cfg entry manually (or type
> it live from a grub2 rescue shell) an example is also here:
> http://forums.freebsd.org/showthread.php?p=85122#post85122
> but note as I said before if you want to boot a 9.1+ kernel directly
> w/o loader you need a grub 2.00 version that has the patch mentioned
> here: (that's now in debian and in FreeBSD ports but might not be
> in other grub2 versions floating around)
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=699002
> Tom
>
HTH, :)
> Juergen
I tried to boot the FreeBSD partition directly from Super Grub2 Disk with chainloader +1, but was not successful.
I think some FreeBSD boot code is in a small boot partition such as I have on the USB-stick installations, installed with gpart.
I wonder if "linux16 memdisk" from grub2 is the same as "KERNEL memdisk" in syslinux: was planning to try it on FreeDOS 1.1 installation fd11src.iso .
I also have a memdisk in the latest syslinux installed from FreeBSD ports.
Once FreeBSD boots from the USB stick, it accesses the GPT partitions OK as far as I can tell.
I could even check with a USB-stick installation of NetBSD, though NetBSD is much less stable than FreeBSD on my modern hardware.
I was even thinking of making a giant floppy image, not to write to an actual disk, but to boot via grub2 or possibly grub4dos.
I would copy /boot but not including the modules to another directory, apply makefs, mdconfig, mount this image, and bsdlabel.
I did something like that with NetBSD 5.1_STABLE i386, and it worked with grub4dos.
I would of course have to interrupt the boot to be able to specify the root file system, as I did with NetBSD, or maybe put into loader.conf .
map --mem --heads=16 --sectors-per-track=63 (hd0,2)/boot2/nbffs51c.img (fd0)
map --hook
rootnoverify (fd0)
chainloader (fd0)+1
boot
and hit the spacebar in time to get the boot menu, so I coulld type
boot netbsd -a
to specify the root file system, or I could boot any other kernel present in the 40 MB "floppy" image.
Grub4dos, being born from DOS, requires setting a (fictitious here) disk geometry.
Tom
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