[PATCH] grub-install: check for arm-efi as a default target

[Steve McIntyre <93sam@debian.org>]

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.

Split out the code to (maybe) load the efivar module and check for
/sys/firmware/efi into a common helper routine is_efi_system()

Signed-off-by: Steve McIntyre <93sam@debian.org>
---
 grub-core/osdep/basic/platform.c |  6 ++++++
 grub-core/osdep/linux/platform.c | 46 +++++++++++++++++++++++++++++++---------
 include/grub/util/install.h      |  3 +++
 util/grub-install.c              |  2 +-
 4 files changed, 46 insertions(+), 11 deletions(-)

diff --git a/grub-core/osdep/basic/platform.c b/grub-core/osdep/basic/platform.c
index 4b5502aeb..a7dafd85a 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 775b6c031..5cb7bf923 100644
--- a/grub-core/osdep/linux/platform.c
+++ b/grub-core/osdep/linux/platform.c
@@ -97,16 +97,19 @@ read_platform_size (void)
   return ret;
 }
 
-const char *
-grub_install_get_default_x86_platform (void)
-{ 
+/* Are we running on an EFI-based system? */
+static int
+is_efi_system (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.
-   */
+     Linux uses efivarfs (mounted on /sys/firmware/efi/efivars)
+     to access the EFI variable store.
+     Some legacy systems may still use the deprecated efivars
+     interface (accessed through /sys/firmware/efi/vars).
+     Where both are present, libefivar will use the former in
+     preference, so attempting to load efivars will not interfere
+     with later operations.
+  */
   grub_util_exec_redirect_all ((const char * []){ "modprobe", "efivars", NULL },
 			       NULL, NULL, "/dev/null");
 
@@ -114,13 +117,36 @@ grub_install_get_default_x86_platform (void)
   if (is_not_empty_directory ("/sys/firmware/efi"))
     {
       grub_util_info ("...found");
+      return 1;
+    }
+  else
+    {
+      grub_util_info ("... not found");
+      return 0;
+    }
+}
+
+const char *
+grub_install_get_default_arm_platform (void)
+{
+  if (is_efi_system())
+    return "arm-efi";
+  else
+    return "arm-uboot";
+}
+
+const char *
+grub_install_get_default_x86_platform (void)
+{ 
+  if (is_efi_system())
+    {
       if (read_platform_size() == 64)
 	return "x86_64-efi";
       else
 	return "i386-efi";
     }
 
-  grub_util_info ("... not found. Looking for /proc/device-tree ..");
+  grub_util_info ("Looking for /proc/device-tree ..");
   if (is_not_empty_directory ("/proc/device-tree"))
     {
       grub_util_info ("...found");
diff --git a/include/grub/util/install.h b/include/grub/util/install.h
index af2bf65d7..80a51fcb1 100644
--- a/include/grub/util/install.h
+++ b/include/grub/util/install.h
@@ -209,6 +209,9 @@ 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);
 
 int
diff --git a/util/grub-install.c b/util/grub-install.c
index 4a0a66168..1d68cc5bb 100644
--- a/util/grub-install.c
+++ b/util/grub-install.c
@@ -319,7 +319,7 @@ 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__)
-- 
2.11.0