Subject: [PATCH 3/3] vm: Support EFI boot in base image.

From: Marius Bakke <[email-masked]>
Date: Sun, 7 May 2017 16:36:47 +0200

* gnu/system/vm.scm (qemu-image): Add GRUB-EFI to inputs. Append 40MB
EFI System Partition.
* gnu/build/vm.scm (initialize-hard-disk): Generate grub EFI blob when ESP is
present.
---
 gnu/build/vm.scm  | 37 ++++++++++++++++++++++++++++++++++++-
 gnu/system/vm.scm | 14 +++++++++++---
 2 files changed, 47 insertions(+), 4 deletions(-)

diff --git a/gnu/build/vm.scm b/gnu/build/vm.scm
index ad39e29ce..a1f419776 100644
--- a/gnu/build/vm.scm
+++ b/gnu/build/vm.scm
@@ -27,6 +27,7 @@
   #:use-module (gnu build linux-boot)
   #:use-module (gnu build install)
   #:use-module (guix records)
+  #:use-module (ice-9 format)
   #:use-module (ice-9 match)
   #:use-module (ice-9 regex)
   #:use-module (srfi srfi-1)
@@ -340,9 +341,16 @@ passing it a directory name where it is mounted."
     "Return the first partition found with the boot flag set."
     (member 'boot (partition-flags partitions)))
 
+  (define (esp-partition? partitions)
+    "Return the first EFI System Partition."
+    (member 'esp (partition-flags partitions)))
+
   (let* ((partitions (initialize-partition-table device partitions))
          (root       (find partition-bootable? partitions))
-         (target     "/fs"))
+         (esp        (find esp-partition? partitions))
+         (target     "/fs")
+         ;; Grub expects EFI System Partitions to be mounted here.
+         (efi-directory (string-append target "/boot/efi")))
     (unless root
       (error "no bootable partition specified" partitions))
 
@@ -352,6 +360,33 @@ passing it a directory name where it is mounted."
     (mkdir-p target)
     (mount (partition-device root) target (partition-file-system root))
     (install-boot-config bootcfg bootcfg-location target)
+
+    ;; If we have an ESP partition, generate a self-contained grub EFI
+    ;; image and write it to a location known by most firmwares.
+    (when esp
+      (display "mounting EFI system partition...\n")
+      (mkdir-p efi-directory)
+      (mount (partition-device esp) efi-directory
+             (partition-file-system esp))
+      (mkdir-p (string-append efi-directory "/EFI/BOOT"))
+
+      ;; Grub needs a tmpdir to prepare the image.
+      (setenv "TMPDIR" (string-append target "/tmp"))
+      ;; It also requires a tiny configuration file telling the
+      ;; memdisk where to find the real thing. TODO: Delete it.
+      (with-output-to-file (string-append target "/tmp/grubdisk.cfg")
+        (lambda _
+          (format #t
+                  "insmod part_msdos~@
+                  search --set=root --label gnu-disk-image~@
+                  configfile /boot/grub/grub.cfg~%")))
+      (system* "grub-mkstandalone" "-O" "x86_64-efi" "-o"
+               (string-append efi-directory "/EFI/BOOT/BOOTX64.EFI")
+               ;; Embed the contents of grubdisk.cfg.
+               (string-append "boot/grub/grub.cfg=" target
+                              "/tmp/grubdisk.cfg"))
+      (umount efi-directory))
+
     (when bootloader-installer
       (bootloader-installer bootloader device target))
 
diff --git a/gnu/system/vm.scm b/gnu/system/vm.scm
index 099e3fac3..04ccc3650 100644
--- a/gnu/system/vm.scm
+++ b/gnu/system/vm.scm
@@ -3,6 +3,7 @@
 ;;; Copyright © 2016 Christopher Allan Webber <[email-masked]>
 ;;; Copyright © 2016 Leo Famulari <[email-masked]>
 ;;; Copyright © 2017 Mathieu Othacehe <[email-masked]>
+;;; Copyright © 2017 Marius Bakke <[email-masked]>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -202,7 +203,7 @@ the image."
                       (guix build utils))
 
          (let ((inputs
-                '#$(append (list qemu parted e2fsprogs dosfstools)
+                '#$(append (list qemu parted e2fsprogs dosfstools grub-efi)
                            (map canonical-package
                                 (list sed grep coreutils findutils gawk))
                            (if register-closures? (list guix) '())))
@@ -227,11 +228,18 @@ the image."
                                #:system-directory #$os.drv))
                   (partitions (list (partition
                                      (size #$(- disk-image-size
-                                                (* 10 (expt 2 20))))
+                                                (* 50 (expt 2 20))))
                                      (label #$file-system-label)
                                      (file-system #$file-system-type)
                                      (flags '(boot))
-                                     (initializer initialize)))))
+                                     (initializer initialize))
+                                    (partition
+                                     ;; Append a small FAT32 partition for
+                                     ;; use with UEFI bootloaders.
+                                     (size (* 40 (expt 2 20)))
+                                     (label "gnu-esp")
+                                     (file-system "vfat")
+                                     (flags '(esp))))))
              (initialize-hard-disk "/dev/vda"
                                    #:partitions partitions
                                    #:bootloader
-- 
2.12.2