Boot arch from iso and grub2

Question

Hello,
I'm trying configure grub2 for boot iso image of arch but don't work:
My grub.cfg entry is:
menuentry "ArchLinux ISO" {
        loopback loop (hd0,3)/iso/arch.iso
        linux    (loop)/boot/vmlinuz26 findiso=/iso/arch.iso lang=en locale=en_US.UTF-8 archisolabel=ARCHISO_KE1AECIE ramdisk_size=75%
        initrd   (loop)/boot/archiso_pata.img
        boot
Arch start correctly boot fail and hope 30 seconds for image of /dev/archiso, I think.
Is the above entry correct?.
Regards.

Answer 1

I wouldn't really call it a bug. It is more like an enhancement that Arch Linux does not currently have, AFAIK.
example:
menuentry "Arch Linux 2009.08 netinstall 64bit" {
     loopback loop /boot/iso/archlinux-2009.08-netinstall-x86_64.iso
     linux (loop)/boot/vmlinuz26 lang=en locale=en_US.UTF-8 archisolabel=ARCHISO_OHD8FOH5 ramdisk_size=75%
     initrd (loop)/boot/archiso_pata.img
What happens with the grub2 is as follows:
loopback loop /boot/iso/archlinux-2009.08-netinstall-x86_64.iso
1) mount the iso image as a loopback
linux (loop)/boot/vmlinuz26 lang=en locale=en_US.UTF-8 archisolabel=ARCHISO_OHD8FOH5 ramdisk_size=75%
2) load the kernel from the iso image (and pass command line options)
initrd (loop)/boot/archiso_pata.img
3) load the initd from the iso image
The problem comes after this.
Once the kernel and the initd are loaded grub2 leaves the picture, as well as the loopback iso image.
The loaded kernel starts the boot process and looks for the files/filesystem it expects to be there.
But it can't find it because the iso loopback device is gone (or as far as it knows, never was there to begin with).
To get around this problem many distros include kernel command line options such as:
iso-scan/filename, findiso, and isofrom
These command line options are pretty much scripts to find and mount the iso image and use it as the root partition. Much like what we did with grub2.
I don't know if the command line options are part of the initd or the kernel itself, but either way I would like to see it as part of Arch Linux default iso.
If I knew how to modify the initd I would make a patch for it or the iso as a whole, but my knowledge doesn't go that far