Avoiding best-effort

[Samuel Thibault <samuel.thibault@ens-lyon.org>]

Hello,

There's a concern with the way grub menu entries work: even if a command
fails, grub continues with others, like bash's "best-effort" way.  This
leads to difficult-to-diagnose results: say for instance

multiboot /boot/mykernel
module /boot/initrd
module /boot/inittask

and initrd is too big for the memory for instance.  The actual error
message that the user will be able to read is "rd0: no such device",
because grub will silently ignore the initrd load failure.

It'd be better to at least have a way to show the actual error.  I've
talked a bit with phcoder, the kind of solutions we've come with are

- "set -e" command, to disable best-effort
- shell-like "&&" to chain commands only if they succeed
- introduce a small delay when printing error messages, to keep best
  effort while still showing the actual grub error.

Thoughts?

Samuel