On Fri, Sep 30, 2016 at 11:07 AM, Richard Ryniker <ryniker(a)alum.mit.edu> wrote:
Works for me. I used a Samsung 940X laptop and a Sandisk 80GB USB3
This is a UEFI machine, and I installed using manual partitioning to
re-use partitions on the external device, which contained an old Fedora
23 system. My purpose here was to preserve an encrypted /home partition.
/boot, /boot/efi, /root and a swap partition were reformatted by the
installer for the F25 system.
In order to boot from the external drive, I must use the EFI boot loader
- press F10 during start to display a list of boot devices, then select
the SanDisk USB drive.
Just a guess, but I think that when the USB stick isn't present, the
firmware is removing what it considers to be a stale NVRAM boot entry.
Or it's reordering the boot priority. Otherwise the stick would be
booted by default, if present.
The internal drive for this machine dual boots Fedora 24 and
Only the external drive was used by Anaconda for the F25 installation.
It might be possible to update GRUB on the internal drive so it can boot
F25 from the external drive, but I rather like the present state where no
change was made to the internal storage medium.
The boot manager aspects of GRUB are weak, it still depends on static
configuration rather than dynamic discovery. Discovery is difficult as
os-prober's existence and history shows. There's a proposed standard
to help, but there's no meaningful agreement on it among any of the
But yes, it's possible to statically get a boot entry into GRUB but
then it appears as if it's a valid option even when the stick isn't
present. If the stick has to be recreated/replaced, then that boot
entry won't work.