[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.

Heavily inspired by the existing code for x86.

Signed-off-by: Steve McIntyre <93sam@debian.org>
---
 grub-core/osdep/basic/platform.c |  6 ++++++
 grub-core/osdep/linux/platform.c | 24 ++++++++++++++++++++++++
 include/grub/util/install.h      |  3 +++
 util/grub-install.c              |  2 +-
 4 files changed, 34 insertions(+), 1 deletion(-)

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..a3f9e9d28 100644
--- a/grub-core/osdep/linux/platform.c
+++ b/grub-core/osdep/linux/platform.c
@@ -98,6 +98,30 @@ 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"))
+    {
+      grub_util_info ("...found");
+      return "arm-efi";
+    }
+
+  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 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