Grub

[ruffwoof]

Another option that may (or not) be of use :

I have grub4dos installed to my mbr, that includes a grldr file being installed in the / folder. That reads menu.lst and one of the settings I have is to chain to the grub menu.lst

# menu.lst
color white/blue black/cyan white/black cyan/black
timeout 1
default 0

title Debian
find --set-root /boot/grub/menu.lst
configfile /boot/grub/menu.lst
commandline

alongside that I have other sections that boot alternatives (puppy linux ....etc.).

When I boot I see that grub4dos menu, which after the default timeout pops up the grub (debian) menu.lst ... which after its default timeout boots up Debian.

Grub4dos can boot from fat or ext. Old but still works fine for my needs. Basically you format the disk, set its boot flag on (using gparted perhaps), then install grub4dos (which loads the mbr and creates grldr and a template menu.lst) ... and then set it up (edit menu.lst) how you like.

[phenest]

Sorry to come in a bit late, but I noticed something odd, although I could be wrong:

start debian and go to the terminal
then give the command: sudo grub-install /dev/sdX
/dev/sdX is your external disk: probably: /dev/sdb

Thanks Peer for the answer but I could not install it :

grub-install : attention : Le système de fichiers « ext2 » ne prend pas en charge l'embarquage.
grub-install : attention : L'embarquage est impossible. GRUB ne peut être installé sur cette configuration qu'en utilisant les listes de blocs. Cependant, les listes de blocs ne sont PAS fiables et leur utilisation est déconseillée..
grub-install : erreur : refus de continuer avec les listes de blocs.

Did you try to install Grub to a partition? This is a common error.

[babak]

You can check with qparted if you usb device has bootflag

boot flag is on sdc1

but it still refuses to boot.

[babak]

Sorry to come in a bit late, but I noticed something odd, although I could be wrong:

.
grub-install : erreur : refus de continuer avec les listes de blocs.

Did you try to install Grub to a partition? This is a common error.[/quote]

I tried to install on sdc1 and it did not work. Then I installed it on sdc. It was installed with no error but does not work.

[phenest]

It was installed with no error but does not work.

Does it work with either of your computers? Or neither?

[babak]

Originaly I installed a dual boot on an XP. Debian is on an external HD. It works fine. But the PC with XP had no usb booting and the Grub is installed on the PC. Now I would like to use the HD on another PC with Win10.

[peer]

Grub-install should normaly work.

But there is an alternative way:
download bootrepairdisk32 (or ..64).iso and burn in on a cd
bootrepairdisk has an option to automatically repair grub.

put the bootrepairdisk in your pc with xp and debian.
start bootrepairdisk (have patience because it will start slowly)
on the screen you will see a popup menu with two options:
- recommended repair
- create a Bootinfo summary
Choose the first option: Recommended repair
then just follow the instructions.
Bootrepairdisk wil then put grub on all available disks (winxp and debian)
So the result will be that grub is installed on your debian disk!!

[Dai_trying]

Now I would like to use the HD on another PC with Win10.

I think this is your problem, you have a legacy mbr grub installation and you are trying to boot on a UEFI machine, (that is I assume Win 10 is installed UEFI) this was the reason I'm not using my external drive as portable OS, like I stated earlier.
It might be possible to also install grub-efi to the external Hdd and then you will need to configure the UEFI menu (on Win 10 machine) to boot from external drive. I have booted external drive with os on my Win 10 machine, but it was installed and configured as UEFI and had a permanent entry in the UEFI boot loaders menu.

The ony other way would be to use "legacy mode" or "CSM" to boot your Win 10 machine, that would allow you to boot your MBR device. I did not want to use that method so I gave up trying.

[babak]

Dai_trying

I upgraded the grub to grub-ufei and reinstalled the grub into /dev/sdc. Nothing changed.

[phenest]

How did you upgrade to EFI? EFI booting requires an EFI System Partition (ESP), and you install it into the ESP and not the root of the drive.

But if you have upgraded to EFI booting, then it won't work on the computer with XP which would require grub legacy.

[Dai_trying]

I have to say I'm not sure you will get it to boot on both systems as they both require a different grub (kinda), but if you can have both grub-efi and normal grub installed together it might be possible but would need someone with better experience than myself as this is the exact reason I didn't continue with my external drive as a portable system.
Good luck though and if you manage to get it working please post here as I would like to know how it's done.

[phenest]

Now there's an interesting challenge.

[babak]

Excuse me the problem is Win10 with its ****** secure boot and/or HP notebook. Even if you disable boot security changing boot sequence is ignored.
There is a long procedure that MS propose to deactivate boot security, but it does not work for my brand new HP.

I will call HP to see if there is a solution.

Thank you all