Re: Grub Troubleshooting

[hoan]

moreover,if I understand your initial intention to boot live debian from 
isoimage sitting on usb_stick ,then your menu_grub.cfg is far from your 
desire .Once grub hands over to kernel ,the kernel is missing lots of 
things,in particular rootfs stuffs

I suggest you do as
menuentry "debian-8.0.0-amd64-DVD-1.iso" {
   set isoloop=/iso/debian-8.0.0-amd64-DVD-1.iso
   search -f -s $isoloop
   loopback loop $isoloop
   linux (loop)/live/vmlinuz findiso=$isoloop rootfstype=iso9660 
boot=live components

   initrd (loop)/live/initrd.img
}
the kernel options allows to find where is sitting your isoimage,the 
partiton's filesystem,and use "live" as script_init
components is proper_debian_init_protocol to know what to setup at this 
stage.(I expect your liveiso is behind /iso/

directory of usbstick.)
To play safe,create /boot/grub/grub.cfg to this usbstick.where grub.cfg 
contains the previous menuentry.


boot with any grub you have,then in grub_console type
configfile (hd_usbstick)/boot/grub/grub.cfg
  enjoy

On 05/06/2016 10:56 AM, wangji wrote:

John Lewis  writes:


Is there a more efficient way to troubleshoot GRUB issues. Right now I
am in a nearly blind, change grub.cfg and boot. If there is an issue
with the initramfs  I am completely blind to how to fix that. Here is a
thread of me trying to resolve a a problem with booting a Debian DVD
with GRUB


http://forums.debian.net/viewtopic.php?f=17=127701.
=8bdd5085a64e7756717cdc1887d7c67a.
from this debianforum link,you wrote:
set imgdevpath="/dev/disk/by-label/multiboot"

Code: Select all
menuentry 'Debian Jessie amd64' {
set isofile='/iso/debian-8.0.0-amd64-DVD-1.iso'
loopback loop $isofile
linux (loop)/install.amd/vmlinuz
initrd (loop)/install.amd/initrd.gz
}

grub environment is totally independent of linux's
env-kernel_initramfs_world- all you can do is to hand over
some parameters['s locations].
On real machine once grub gets into your grub's menu it needs to have the
right $root (eventually $prefix).

The imgdevpath is in nix's world,so your emulator can get grasp of it,but
not grub 

On bare metal your grub's menu needs surely something of the kinds
  
"search -f -s $isofile"  before the loopback line.


As demo of multiboot of linuxaio-fedora23-amd64.iso which only boots in
legacy CSM mode.A correct grub.cfg is enough to make it boot on uefi_pc
using any current grub2-efi stick .
see:
https://sourceforge.net/projects/toysbox/files/linuxaio-fedora23-amd64 Put a
tiger grub on it/




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Re: Grub Troubleshooting

[wangji]

John Lewis  writes:

> 
> Is there a more efficient way to troubleshoot GRUB issues. Right now I
> am in a nearly blind, change grub.cfg and boot. If there is an issue
> with the initramfs  I am completely blind to how to fix that. Here is a
> thread of me trying to resolve a a problem with booting a Debian DVD
> with GRUB
>
>
> http://forums.debian.net/viewtopic.php?f=17=127701.
> =8bdd5085a64e7756717cdc1887d7c67a.
> from this debianforum link,you wrote:
> set imgdevpath="/dev/disk/by-label/multiboot"
>
> Code: Select all
>menuentry 'Debian Jessie amd64' {
>set isofile='/iso/debian-8.0.0-amd64-DVD-1.iso'
>loopback loop $isofile
>linux (loop)/install.amd/vmlinuz
>initrd (loop)/install.amd/initrd.gz
>}

grub environment is totally independent of linux's
env-kernel_initramfs_world- all you can do is to hand over 
some parameters['s locations].
On real machine once grub gets into your grub's menu it needs to have the
right $root (eventually $prefix).

The imgdevpath is in nix's world,so your emulator can get grasp of it,but
not grub 

On bare metal your grub's menu needs surely something of the kinds  
 
"search -f -s $isofile"  before the loopback line. 

As demo of multiboot of linuxaio-fedora23-amd64.iso which only boots in
legacy CSM mode.A correct grub.cfg is enough to make it boot on uefi_pc
using any current grub2-efi stick .
see:
https://sourceforge.net/projects/toysbox/files/linuxaio-fedora23-amd64 Put a
tiger grub on it/




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