Solved loopback loop not working

B

balanga

I'm trying to get a Grub menuentry working and it fails with:-
error: disk 'loop' not found
Click to expand...

The menuentry consists of:-
Code: 
menuentry "Ubuntu" {
    set isofile="/iso/ubuntu-14.04.4-desktop-i386.iso"
    loopback loop (hd0,8)$isofile
    linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$isofile noprompt noeject toram
    initrd (loop)/casper/initrd.lz
}

This works fine when using Grub under Linux but fails under FreeBSD.

I notice that there is a program /boot/grub/i386-pc/loopback.mod which I presume is responsible processing loopbacks so I guess the problem is the lack of a 'loop' on FreeBSD. Can I use something like mdconfig() to achieve a similar effect?
 
balanga said:
I notice that there is a program /boot/grub/i386-pc/loopback.mod which I presume is responsible processing loopbacks so I guess the problem is the lack of a 'loop' on FreeBSD. Can I use something like mdconfig() to achieve a similar effect?
Click to expand...
I don't think so. mdconfig could only be used after FreeBSD was booted. This case you want to boot Ubuntu's iso, don't you? You're left with grub2, alone.
 
balanga said:
I'm trying to get a Grub menuentry working and it fails with:-


The menuentry consists of:-
Code: 
menuentry "Ubuntu" {
    set isofile="/iso/ubuntu-14.04.4-desktop-i386.iso"
    loopback loop (hd0,8)$isofile
    linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$isofile noprompt noeject toram
    initrd (loop)/casper/initrd.lz
}

This works fine when using Grub under Linux but fails under FreeBSD.
Click to expand...
I think you need something like insmod ufs2. Please try if it works.
 
I'm trying to figure out why loopback loop works on one system but not on another. The Grub menu entries are the same. The difference is that one grub.cfg is installed on a Linux partition and the other is on a FreeBSD partition.

An explanation of the loopback command can be found here:-

GNU GRUB Manual 2.12

GNU GRUB Manual 2.12
www.gnu.org

If it's an internal Grub command shouldn't it work the same way?
 
blackdog said:
I think you need something like insmod ufs2. Please try if it works.
Click to expand...

You need insmod ufs2 if you want to boot from a ufs2 partition. I'm trying to boot Ubuntu from an ISO which resides on a FAT32 partition. Grub can locate the ISO from:-
Code: 
set isofile="/iso/ubuntu-14.04.4-desktop-i386.iso"
loopback loop (hd0,8)$isofile
Specifying the partition type isn't even necessary in this case.
 
I got some idea from here. It could be something (hd0, gptX) or (hd0, msdosXs). Please tell me it if it works.
 
balanga said:
You need insmod ufs2 if you want to boot from a ufs2 partition. I'm trying to boot Ubuntu from an ISO which resides on a FAT32 partition. Grub can locate the ISO from:-
Code: 
set isofile="/iso/ubuntu-14.04.4-desktop-i386.iso"
loopback loop (hd0,8)$isofile
Specifying the partition type isn't even necessary in this case.
Click to expand...
You didn't tell us about your setup, so I assumed it's on UFS2.
 
As blackdog suggested, it could be a problem with the device naming. At the grub boot menu drop to grub command line, execute ls, compaire listed devices names to disk menu entry (hd0,8).
 
I think I've got to the bottom of the problem... I must have been misreading the error msg.

The loopback loop error was caused by an error in the previous line :oops:

So, I've managed to successfully boot Ubuntu from my multiboot USB stick. I'll see if I can get a few more systems working.
 
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