Subject: [bug#41011] [PATCH] gnu: grub: Support for network boot via tftp/nfs.

From: Stefan <[email-masked]>
Date: Thu, 21 May 2020 20:40:44 +0200

* gnu/bootloader/grub.scm (grub-efi-net-bootloader): New efi bootloader for
network booting via tftp/nfs, prepared for chain loading.
(make-grub-efi-net-bootloader): New macro to define a customized bootloader
based on 'grub-efi-net-bootloader'.
(install-grub-efi-net): New bootloader installer for tftp.
(grub-root-search): Adding support for tftp root.
(eye-candy): Use 'gfxterm' for all systems if selected via 'terminal-outputs'.
* gnu/system.scm (read-boot-parameters): Prevent devices with ":/" from being
treated as a file system label.
---
 gnu/bootloader/grub.scm | 125 +++++++++++++++++++++++++++++-----------
 gnu/system.scm          |   3 +-
 2 files changed, 94 insertions(+), 34 deletions(-)

diff --git a/gnu/bootloader/grub.scm b/gnu/bootloader/grub.scm
index bb40c551a7..2b0ecec279 100644
--- a/gnu/bootloader/grub.scm
+++ b/gnu/bootloader/grub.scm
@@ -23,7 +23,7 @@
 
 (define-module (gnu bootloader grub)
   #:use-module (guix records)
-  #:use-module ((guix utils) #:select (%current-system))
+  #:use-module ((guix utils) #:select (%current-system %current-target-system))
   #:use-module (guix gexp)
   #:use-module (gnu artwork)
   #:use-module (gnu bootloader)
@@ -47,6 +47,8 @@
 
             grub-bootloader
             grub-efi-bootloader
+            make-grub-efi-net-bootloader
+            grub-efi-net-bootloader
             grub-mkrescue-bootloader
             grub-minimal-bootloader
 
@@ -140,36 +142,20 @@ file with the resolution provided in CONFIG."
 concerned with graphics mode, background images, colors, and all that.
 STORE-DEVICE designates the device holding the store, and STORE-MOUNT-POINT is
 its mount point; these are used to determine where the background image and
-fonts must be searched for.  SYSTEM must be the target system string---e.g.,
-\"x86_64-linux\".  BTRFS-STORE-SUBVOLUME-FILE-NAME is the file name of the
-Btrfs subvolume, to be prepended to any store path, if any."
-  (define setup-gfxterm-body
-    (let ((gfxmode
-           (or (and-let* ((theme (bootloader-configuration-theme config))
-                          (gfxmode (grub-theme-gfxmode theme)))
-                 (string-join gfxmode ";"))
-               "auto")))
-
-      ;; Intel and EFI systems need to be switched into graphics mode, whereas
-      ;; most other modern architectures have no other mode and therefore
-      ;; don't need to be switched.
-
-      ;; XXX: Do we really need to restrict to x86 systems?  We could imitate
-      ;; what the GRUB default configuration does and decide based on whether
-      ;; a user provided 'gfxterm' in the terminal-outputs field of their
-      ;; bootloader-configuration record.
-      (if (string-match "^(x86_64|i[3-6]86)-" system)
-          (format #f "
-  set gfxmode=~a
-  insmod all_video
-  insmod gfxterm~%" gfxmode)
-          "")))
-
+fonts must be searched for.  BTRFS-STORE-SUBVOLUME-FILE-NAME is the file name
+of the Btrfs subvolume, to be prepended to any store path, if any."
   (define (setup-gfxterm config font-file)
     (if (memq 'gfxterm (bootloader-configuration-terminal-outputs config))
-        #~(format #f "if loadfont ~a; then
-  setup_gfxterm
-fi~%" #+font-file)
+        #~(format #f "
+if loadfont ~a; then
+  set gfxmode=~a
+  insmod all_video
+  insmod gfxterm
+fi~%"
+                  #$font-file
+                  #$(string-join
+                      (grub-theme-gfxmode (bootloader-theme config))
+                      ";"))
         ""))
 
   (define (theme-colors type)
@@ -190,8 +176,6 @@ fi~%" #+font-file)
 
   (and image
        #~(format #$port "
-function setup_gfxterm {~a}
-
 # Set 'root' to the partition that contains /gnu/store.
 ~a
 
@@ -206,7 +190,6 @@ else
   set menu_color_normal=cyan/blue
   set menu_color_highlight=white/blue
 fi~%"
-                 #$setup-gfxterm-body
                  #$(grub-root-search store-device font-file)
                  #$(setup-gfxterm config font-file)
                  #$(grub-setup-io config)
@@ -313,6 +296,9 @@ code."
         ((? file-system-label? label)
          (format #f "search --label --set ~a"
                  (file-system-label->string label)))
+        ((? (lambda (device)
+              (and (string? device) (string-contains device ":/"))) nfs-uri)
+         "set root=(tftp)")
         ((or #f (? string?))
          #~(format #f "search --file --set ~a" #$file)))))
 
@@ -454,6 +440,68 @@ fi~%"))))
                       "--bootloader-id=Guix"
                       "--efi-directory" target-esp))))
 
+(define (install-grub-efi-net efi-subdir)
+  "Define a grub-efi bootloader installer for installation in EFI-SUBDIR,
+which is usually \"efi/boot\" or \"efi/Guix\"."
+  (let* ((arch (car (string-split (or (%current-target-system)
+                                      (%current-system))
+                                  #\-)))
+         (efi-bootloader-link (string-append "boot"
+                                             (match arch
+                                               ("i686" "ia32")
+                                               ("x86_64" "x64")
+                                               ("arm" "arm")
+                                               ("armhf" "arm")
+                                               ("aarch64" "aa64")
+                                               ("riscv" "riscv32")
+                                               ("riscv64" "riscv64"))
+                                             ".efi"))
+         (efi-bootloader (string-append (match arch
+                                          ("i686" "i386")
+                                          ("x86_64" "x86_64")
+                                          ("arm" "arm")
+                                          ("armhf" "arm")
+                                          ("aarch64" "arm64")
+                                          ("riscv" "riscv32")
+                                          ("riscv64" "riscv64"))
+                                        "-efi/core.efi")))
+    #~(lambda (bootloader target mount-point)
+        "Install GRUB as e.g. \"bootx64.efi\" or \"bootarm64.efi\" \"into
+EFI-SUBDIR, which is usually \"efi/boot\" or \"efi/Guix\" below the directory
+TARGET for the system whose root is mounted at MOUNT-POINT."
+        (let* ((mount-point-list (delete "" (string-split mount-point #\/)))
+               (target-list (delete "" (string-split target #\/)))
+               (net-dir
+                (string-append "/" (string-join (append
+                                                 mount-point-list
+                                                 target-list)
+                                                "/")))
+               (subdir #$efi-subdir)
+               (efi-bootloader-link
+                (string-append net-dir "/" subdir "/" #$efi-bootloader-link))
+               (store-name (car (delete "" (string-split bootloader #\/))))
+               (store
+                ;; Use target-list to construct a "../gnu" link with a correct
+                ;; number of "../" to the store.
+                (string-join (append (make-list (length target-list) "..")
+                                     (list store-name))
+                             "/"))
+               (store-link (string-append net-dir "/" store-name)))
+          ;; Tell 'grub-install' that there might be a LUKS-encrypted /boot or
+          ;; root partition.
+          (setenv "GRUB_ENABLE_CRYPTODISK" "y")
+          (invoke/quiet (string-append bootloader "/bin/grub-mknetdir")
+                        (string-append "--net-directory=" net-dir)
+                        (string-append "--subdir=" subdir))
+          (false-if-exception
+            (delete-file efi-bootloader-link))
+          (symlink #$efi-bootloader
+                   efi-bootloader-link)
+          (false-if-exception
+            (delete-file store-link))
+          (symlink store
+                   store-link)))))
+
 ^L
 
 ;;;
@@ -483,7 +531,18 @@ fi~%"))))
    (name 'grub-efi)
    (package grub-efi)))
 
-(define* grub-mkrescue-bootloader
+(define-syntax-rule (make-grub-efi-net-bootloader bootloader-name target efi-subdir)
+    (define bootloader-name
+       (bootloader
+          (inherit grub-bootloader)
+          (name (quote bootloader-name))
+          (package grub-efi)
+          (installer (install-grub-efi-net efi-subdir))
+          (configuration-file (string-append target "/" efi-subdir "/grub.cfg")))))
+
+(make-grub-efi-net-bootloader grub-efi-net-bootloader "boot" "efi/boot")
+
+(define grub-mkrescue-bootloader
   (bootloader
    (inherit grub-efi-bootloader)
    (package grub-hybrid)))
diff --git a/gnu/system.scm b/gnu/system.scm
index d929187695..2035235549 100644
--- a/gnu/system.scm
+++ b/gnu/system.scm
@@ -301,7 +301,8 @@ file system labels."
       ((? string? device)
        ;; It used to be that we would not distinguish between labels and
        ;; device names.  Try to infer the right thing here.
-       (if (string-prefix? "/dev/" device)
+       (if (or (string-prefix? "/dev/" device)
+               (string-contains device ":/")) ; nfs
            device
            (file-system-label device)))))
 
-- 
2.26.0