util/grub-mkrescue: use capitalised paths for removable EFI images

Per UEFI Specification, section 3.4.1.1:

... If FilePathList[0] points to a device that supports the
EFI_SIMPLE_FILE_SYSTEM_PROTOCOL, then the system firmware will attempt to boot
from a removable media FilePathList[0] by adding a default file name in the
form \EFI\BOOT\BOOT{machine type short-name}.EFI.

While FAT < 32 filesystems are not case sensitive (which grub-mkrescue creates
as a FAT12 image via mformat with a size of 2.88MiB), it seems that
some of Loongson's LoongArch-based firmware (namely those found on their
latest XA61200 boards) seems to treat this file system as case-sensitive. In
this case, at least the XA61200 board seems incapable of identifying
/efi/boot/bootloongarch64.efi as a valid removable EFI image.

In any case, according to the UEFI Specification, all paths and image
filenames should be capitalised (with the exception of BOOTx64.EFI, according
to section 3.5.1.1, for some reason) to stay compliant. The Loongson case is
only one example of users running into buggy firmware and unbootable GRUB
ISO images.

Signed-off-by: Mingcong Bai <[email protected]>

Author: MingcongBai

util/grub-mkrescue.c

@@ -769,8 +769,8 @@ main (int argc, char *argv[])
       || source_dirs[GRUB_INSTALL_PLATFORM_RISCV64_EFI])
     {
       FILE *f;
-      char *efidir_efi = grub_util_path_concat (2, iso9660_dir, "efi");
-      char *efidir_efi_boot = grub_util_path_concat (3, iso9660_dir, "efi", "boot");
+      char *efidir_efi = grub_util_path_concat (2, iso9660_dir, "EFI");
+      char *efidir_efi_boot = grub_util_path_concat (3, iso9660_dir, "EFI", "BOOT");
       char *imgname, *img32, *img64, *img_mac = NULL;
       char *efiimgfat, *iso_uuid_file, *diskdir, *diskdir_uuid;
       grub_install_mkdir_p (efidir_efi_boot);
@@ -792,39 +792,39 @@ main (int argc, char *argv[])
       free (diskdir_uuid);
       free (diskdir);
 
-      imgname = grub_util_path_concat (2, efidir_efi_boot, "bootia64.efi");
+      imgname = grub_util_path_concat (2, efidir_efi_boot, "BOOTIA64.EFI");
       make_image_fwdisk_abs (GRUB_INSTALL_PLATFORM_IA64_EFI, "ia64-efi", imgname);
       free (imgname);
 
       grub_install_push_module ("part_apple");
-      img64 = grub_util_path_concat (2, efidir_efi_boot, "bootx64.efi");
+      img64 = grub_util_path_concat (2, efidir_efi_boot, "BOOTx64.EFI");
       make_image_abs (GRUB_INSTALL_PLATFORM_X86_64_EFI, "x86_64-efi", img64);
       grub_install_pop_module ();
 
       grub_install_push_module ("part_apple");
-      img32 = grub_util_path_concat (2, efidir_efi_boot, "bootia32.efi");
+      img32 = grub_util_path_concat (2, efidir_efi_boot, "BOOTIA32.EFI");
       make_image_abs (GRUB_INSTALL_PLATFORM_I386_EFI, "i386-efi", img32);
       grub_install_pop_module ();
 
-      imgname = grub_util_path_concat (2, efidir_efi_boot, "bootarm.efi");
+      imgname = grub_util_path_concat (2, efidir_efi_boot, "BOOTARM.EFI");
       make_image_abs (GRUB_INSTALL_PLATFORM_ARM_EFI, "arm-efi", imgname);
       free (imgname);
 
-      imgname = grub_util_path_concat (2, efidir_efi_boot, "bootaa64.efi");
+      imgname = grub_util_path_concat (2, efidir_efi_boot, "BOOTAA64.EFI");
       make_image_abs (GRUB_INSTALL_PLATFORM_ARM64_EFI, "arm64-efi", imgname);
       free (imgname);
 
-      imgname = grub_util_path_concat (2, efidir_efi_boot, "bootloongarch64.efi");
+      imgname = grub_util_path_concat (2, efidir_efi_boot, "BOOTLOONGARCH64.EFI");
       make_image_fwdisk_abs (GRUB_INSTALL_PLATFORM_LOONGARCH64_EFI,
 			     "loongarch64-efi",
 			     imgname);
       free (imgname);
 
-      imgname = grub_util_path_concat (2, efidir_efi_boot, "bootriscv32.efi");
+      imgname = grub_util_path_concat (2, efidir_efi_boot, "BOOTRISCV32.EFI");
       make_image_abs (GRUB_INSTALL_PLATFORM_RISCV32_EFI, "riscv32-efi", imgname);
       free (imgname);
 
-      imgname = grub_util_path_concat (2, efidir_efi_boot, "bootriscv64.efi");
+      imgname = grub_util_path_concat (2, efidir_efi_boot, "BOOTRISCV64.EFI");
       make_image_abs (GRUB_INSTALL_PLATFORM_RISCV64_EFI, "riscv64-efi", imgname);
       free (imgname);