Subject: [alpine-user] booting Alpine ISO on USB via GRUB

From: Wayne <[email-masked]>
Date: Tue, 24 Jul 2018 16:52:58 -0400

ahoy all,

  first thanks for Alpine, never have seen packages install so  
quickly!  testing currently and getting ready to install it permanently.

  but first for various reasons i need to boot the Alpine ISO from an  
external USB drive using GRUB (installed on USB drive) on a BIOS  
non-EFI computer.  in particular i have a GPT formatted USB flash  
drive with the following partition layout:

partition 1: ESP (FAT32 EFI System Partition)
partition 2: BIOS boot (GRUB boot partition needed to boot GRUB on GPT  
disks using BIOS)
partition 3: storage (FAT32 where boot/grub directory and ISOs are stored)

again, though the USB drive is GPT formatted and has an ESP partition,  
we are trying to boot the ISO with a BIOS only computer, so no  
EFI/UEFI stuff.  using this drive and GRUB config i am able to boot  
other ISOs e.g. System Rescue CD, Memtest86+, etc, just not Alpine ..  
yet :)

  after much researching and culling information from various sources,  
the best /NON-WORKING/ menu entry in grub.cfg that i have thus far is:

set timeout=10
set default=0

submenu "Alpine Linux" {

    menuentry "extended 3.8.0 x86-64" {
        set isofile="/home/share/Alpine/alpine-extended-3.8.0-x86_64.iso"
        loopback loop ${isofile}
        linux (loop)/boot/vmlinuz-vanilla iso-scan/filename=${isofile}  
alpine_dev=usbdisk:vfat BOOT_IMAGE=/boot/vmlinuz-vanilla  
modules=loop,squashfs,sd-mod,usb-storage quiet nomodeset  
initrd=/boot/initramfs-vanilla
        initrd (loop)/boot/initramfs-vanilla
    }

this begins to boot but then ends in

Mounting boot media failed.
initramfs emergency recovery shell launched. Type 'exit' to continue boot

   i am stumped and i have seen others have been asking this[1] or a  
similar[2] question.  i would be happy to update the wiki and answer  
the serverfault question once i get this working.    thanks in advance  
for any solutions, tips, pointers, etc, and again for Alpine.  peace,  
w  PS: i think that the "iso-scan/filename=${isofile}" is Debian  
specific but removing it makes no difference and i have yet to find an  
Alpine equivalent, though i do not find anything like it on the  
current kernel command line used to boot the ISO when dd'd to a USB  
stick

Links:
------
[1] https://wiki.alpinelinux.org/wiki/Talk:Installation
[2]  
https://serverfault.com/questions/882130/alpine-linux-boot-from-iso-stored-inside-an-hard-drive
  https://waynedpj.ingiro.xyz