bootloader: Add u-boot.

* gnu/bootloader/u-boot.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add it.
* doc/guix.texi: Document it.

gnu/bootloader/u-boot.scm

@@ -0,0 +1,47 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2017 David Craven <david@craven.ch>
+;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (gnu bootloader u-boot)
+  #:use-module (gnu bootloader extlinux)
+  #:use-module (gnu bootloader)
+  #:use-module (gnu system)
+  #:use-module (gnu packages bootloaders)
+  #:use-module (guix gexp)
+  #:use-module (guix monads)
+  #:use-module (guix records)
+  #:use-module (guix utils)
+  #:export (u-boot-bootloader))
+
+(define install-u-boot
+  #~(lambda (bootloader device mount-point)
+      (if bootloader
+        (error "Failed to install U-Boot"))))
+
+
+
+;;;
+;;; Bootloader definitions.
+;;;
+
+(define u-boot-bootloader
+  (bootloader
+   (inherit extlinux-bootloader)
+   (name 'u-boot)
+   (package #f)
+   (installer install-u-boot)))