Bug#922104: grub-install: check for arm-efi as a default target

[Steve McIntyre]

Package: src:grub
Version: 2.02+dfsg1-11
Severity: normal
Tags: upstream patch

Hi Colin,

I've already submitted the core of this upstream - see

  http://lists.gnu.org/archive/html/grub-devel/2019-02/msg00018.html

Much like on x86, we can work out if the system is running on top of
EFI firmware. If so, return "arm-efi". If not, fall back to
"arm-uboot" as previously.

Heavily inspired by the existing code for x86.

I'd push this as an MR, but my head is just not in the right place for
handling git-dpm right now :-(

Here's a patch instead, ready to drop into debian/patches. I've
extended the code here in similar fashion to what's already been added
in our version of grub_install_get_default_x86_platform() to check in
the pkglibdir. Otherwise this new code is just the same as I've sent
upstream yesterday.

-- System Information:
Debian Release: 9.7
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable-debug'), (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.9.0-8-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8), LANGUAGE=en_GB.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
-------------- next part --------------
From: Steve McIntyre <93sam at debian.org>
Date: Tue, 12 Feb 2019 02:23:14 +0000
Subject: grub-install: check for arm-efi as a default target

Much like on x86, we can work out if the system is running on top of
EFI firmware. If so, return "arm-efi". If not, fall back to
"arm-uboot" as previously.

Heavily inspired by the existing code for x86.

Signed-off-by: Steve McIntyre <93sam at debian.org>

Bug-Debian: https://bugs.debian.org/XXXXXX
Forwarded: http://lists.gnu.org/archive/html/grub-devel/2019-02/msg00018.html

Patch-Name: grub-install-check-arm-efi.patch
 grub-core/osdep/basic/platform.c |  6 ++++++
 grub-core/osdep/linux/platform.c | 37 +++++++++++++++++++++++++++++++++++++
 include/grub/util/install.h      |  3 +++
 util/grub-install.c              |  2 +-
 5 files changed, 48 insertions(+), 1 deletion(-)
diff --git a/grub-core/osdep/basic/platform.c b/grub-core/osdep/basic/platform.c
index 2ab907976..ac41452e0 100644
--- a/grub-core/osdep/basic/platform.c
+++ b/grub-core/osdep/basic/platform.c
@@ -19,6 +19,12 @@
 #include <grub/util/install.h>
 
 const char *
+grub_install_get_default_arm_platform (void)
+{ 
+  return "arm-uboot";
+}
+
+const char *
 grub_install_get_default_x86_platform (void)
 { 
   return "i386-pc";
diff --git a/grub-core/osdep/linux/platform.c b/grub-core/osdep/linux/platform.c
index 9805c36d4..0110ac655 100644
--- a/grub-core/osdep/linux/platform.c
+++ b/grub-core/osdep/linux/platform.c
@@ -101,6 +101,43 @@ read_platform_size (void)
 }
 
 const char *
+grub_install_get_default_arm_platform (void)
+{ 
+  /*
+     On Linux, we need the efivars kernel modules.
+     If no EFI is available this module just does nothing
+     besides a small hello and if we detect efi we'll load it
+     anyway later. So it should be safe to
+     try to load it here.
+   */
+  grub_util_exec_redirect_all ((const char * []){ "modprobe", "efivars", NULL },
+			       NULL, NULL, "/dev/null");
+
+  grub_util_info ("Looking for /sys/firmware/efi ..");
+  if (is_not_empty_directory ("/sys/firmware/efi"))
+    {
+      const char *pkglibdir = grub_util_get_pkglibdir ();
+      const char *platform;
+      char *pd;
+      int found;
+
+      grub_util_info ("...found");
+      platform = "arm-efi";
+
+      pd = grub_util_path_concat (2, pkglibdir, platform);
+      found = grub_util_is_directory (pd);
+      free (pd);
+      if (found)
+	return platform;
+      else
+	grub_util_info ("... but %s platform not available", platform);
+    }
+
+  grub_util_info ("... not found");
+  return "arm-uboot";
+}
+
+const char *
 grub_install_get_default_x86_platform (void)
 { 
   /*
diff --git a/include/grub/util/install.h b/include/grub/util/install.h
index 3fd46ec30..5783cc4bc 100644
--- a/include/grub/util/install.h
+++ b/include/grub/util/install.h
@@ -205,6 +205,9 @@ void
 grub_install_create_envblk_file (const char *name);
 
 const char *
+grub_install_get_default_arm_platform (void);
+
+const char *
 grub_install_get_default_x86_platform (void);
 
 const char *
diff --git a/util/grub-install.c b/util/grub-install.c
index 6bc96fc8f..fcd6680f1 100644
--- a/util/grub-install.c
+++ b/util/grub-install.c
@@ -348,7 +348,7 @@ get_default_platform (void)
 #elif defined (__ia64__)
    return "ia64-efi";
 #elif defined (__arm__)
-   return "arm-uboot";
+   return grub_install_get_default_arm_platform ();
 #elif defined (__aarch64__)
    return "arm64-efi";
 #elif defined (__amd64__) || defined (__x86_64__) || defined (__i386__)