Installation using usb-stick & grub4dos

Question

I want to install arch using grub4dos without any partitions and iso-writing. Just put iso on usb-stick, make some magic with grub4dos and install arch.
So, Now I can boot arch iso, but my boot from this iso crush.
Grub:
map --heads=0 --sectors-per-track=0 /arch.iso (0xff)
map --hook
root (0xff)
chainloader (0xff)
this code works fine, arch.iso booting fine, that it loads kernel, but can't find device "boot device didn't show up after 30 seconds" because it search for disk-by-label=ARCH-BLABLA, but my usb-stick has FLASH label
I have tried to boot using kernel and initrd commands in grub, without loading arch boot menu - nothing works.
I have tried to change label, in arch boot menu I pressed tab, then change archlabel to FLASH (my usb-stick label), but it still can't find device.
Any ideas?
Last edited by satanalin (2012-03-04 15:14:51)

Answer 1

Since grub4dos is still used for this purpose, and since this topic turns up on google as a first hit for some very generic search terms, I'll add an easy solution.
Arch can easily be booted via it's installation ISO using the OP's method, with a small prior to the initramfs mounting it's filesystems.
after using
map --mem (hd?,?)/path/to/arch.iso (0xff)
map --hook
chainloader (0xff)
boot
GRUB chainloads up the isolinux bootloader from the iso now mapped in memory.
Upon selecting your architecture, isolinux begins the system's transition from real mode to protected mode.
It loads the kernel and initrd correctly from memory back to memory, however once the kernel is bootstrapped, the iso in memory is lost.
The mount's fail because the iso isn't designed to boot via grub4dos memory mapping.
You are however dropped to a rescue shell.
You can now mount the filesystem of the usb that the iso is contained within, and copy it back to memory, and with either a loopback mount or a symlink, you're good to go.
# make a new directory to mount the usb partition
mkdir /usb
# mount the usb partition (you can check with lsblk or blkid both included in the initramfs shell)
mount /dev/sd?? /usb
# copy the iso to the /dev directory
# or similar location that is preferrably passed on to the root filesystem at chroot
cp /usb/path/to/arch.iso /dev/arch.iso
# cleanup after yourself as a best practice i suppose (also want to remove the flashdrive right?)
umount /usb;rmdir /usb
# either of these methods works for me.
losetup -f /dev/arch.iso
# or
ln -s /dev/arch.iso /dev/disk/by-label/ARCH_?????? # being the date on the iso label
# You could also just copy the iso into the /dev/disk/by-label directory with the label as the file name "ARCH_??????"
# exit twice because you drop back into rescue shell the first time.
exit # or [ctrl] + [d]
exit # or [ctrl] + [d]
Arch should boot correctly and quickly!