Re: Exercise: Booting from a LiveUSB ISO and contents on /dev/sda6

[Fajar A. Nugraha]

On Mon, Nov 2, 2015 at 10:27 AM, Philip Rhoades <address@hidden> wrote:

People,

I want to enlarge my root partition on a Fedora 23 x86_64 system and I know I can boot on a LiveUSB stick and use [g]parted from there to do what I want but I thought I would try creating a small partition with the ISO and its contents in it to see if I could do what I want without needing to use the USB stick.

Personally I find it easier to simply have a full linux "rescue" installation instead of using a live one. It would take less than 4GB space, faster, and have more features compared to a live system.

 

The contents of /dev/sda6 is:

dr-xr-xr-x   3 root root       4096 May 22 05:03 EFI
dr-xr-xr-x   2 root root       4096 May 22 05:05 LiveOS
dr-xr-xr-x   2 root root       4096 May 22 05:03 isolinux
drwx------   2 root root      16384 Nov  2 06:08 lost+found
-r--r--r--   1 root root       2460 May 22 05:04 Fedora-Legal-README.txt
-rw-r-----   1 qemu qemu 1007681536 Oct  7 20:14 Fedora-Live-Xfce-x86_64-22-3.iso
-r--r--r--   1 root root       1063 May 22 05:04 LICENSE


I have made a little progress but I still can't get a boot - here is the current state of the relevant section of my grub2.cfg (I have been trying various changes):

menuentry "Fedora 22 XFCE ISO Boot (x86_64 bit)" {
    insmod part_gpt
    set isoname="Fedora-Live-Xfce-x86_64-22-3"
    echo $isoname
    set isofile="${isoname}.iso"
    echo $isofile
    loopback loop (hd0,gpt6)/$isofile
    echo $loop
    linux (loop)/isolinux/vmlinuz0 root=live:CDLABEL=${isoname} rootfstype=auto ro rd.live.image rd.luks=0 rd.md=0 rd.dm=0 iso-scan/filename=${isofile}
    initrd (loop)/isolinux/initrd0.img
}

During the attempted boot I see the first two "echo"s but then get messages that "linux" and "initrd" commands do not exist . . is it something simple I am missing?

IIRC in the past there was a requirement where the loopfile needed to be unfragmented? Can't remember the details though.

Anyway, you can try:

- open a grub command prompt (press "c") instead of selecting the menu, and execute the commands manually. It should be easy-enough since there's tab completion.

- after the "loopback loop" command, you can try typing "ls (loop" and then press tab. It should print out what partitions grub recognize inside the loopback file, and what FS the partition contains. If that works, you can verify whether the paths you wrote for kernel and initrd are correct using tab completion.

Alternatively, since you pretty much only need the kernel and initrd anyway, just copy it to your current system (e.g. /boot/live/kernel and /boot/live/initrd) or a directory in your /dev/sda6. It should help filter-out any grub-loop-related problems. The kernel and initrd will only be needed by grub during startup, and can remain safely unmounted once you're in the live environment.

-- 

Fajar