wip u-boot support

[Danny Milosavljevic]

Hi David,

I thought I'd post a minimal version for U-Boot support without any renames 
that aren't absolutely necessary. In this way, the patch is quite small.

I think I also figured out how to pass the name of the bootloader installation 
executable - that's also included.

Let's see whether it works.

See attachement...

I assume that gnu/system/u-boot.scm already exists.

If it doesn't, I've also attached the latest version of it.

As you can see it's no big deal.

Note that the only reasons <u-boot-configuration> is distinct from 
<grub-configuration> are:
- The field "board" which contains the board name is necessary in 
<u-boot-configuration> but not <grub-configuration>.
- The system config's "operating-system" definition contains a "bootloader" 
field that is actually a bootloader-configuration (rather than the actual 
bootloader package or similar). Hence there would be no way to find out which 
bootloader to install if the configuration wasn't a different data structure.

I'm not sure those are good enough reasons to justify distinguishing them.

It would also be possible to change the system config to something like

(operating-system
  (bootloader grub (bootloader-configuration ...)))

and

(operating-system
  (bootloader (make-u-boot-package "my_great_system") (bootloader-configuration 
...)))

and then drop "board". In that case, <u-boot-configuration> would be the same 
as <grub-configuration> - but grub-configuration supports theming which 
u-boot-configuration doesn't. We could just ignore the theme parts in that 
case, though.

wip-uboot-support.patch
Description: Text Data

u-boot.scm
Description: Text Data