Add optical boot support for ISO images

* UEFI still uses El-Torito for optical boot, so we now also create an 8 MB FAT image with
  the Shells (but without Mosby, since Mosby requires RW media anyway) that can be used for
  optical boot.
* Also, for transposition to case-sensitive file system with pedantic UEFI implementations,
  we now follow the bootloader naming case convention exactly as stated in the specs:
  https://uefi.org/specs/UEFI/2.11/03_Boot_Manager.html#removable-media-boot-behavior
* Closes #14.
* Also update EDK2 to latest for dress rehearsal before the 202511 EDK2 stable release.

Author: pbatard

.github/workflows/linux_gcc_edk2.yml

@@ -29,7 +29,7 @@ jobs:
     steps:
     - name: Checkout repository and submodules
       # Must happen first, else the LoongArch toolchain gets deleted (even with clean: false)
-      uses: actions/checkout@v4
+      uses: actions/checkout@v5
       with:
         # Need fetch-depth: 0 to obtain the EDK2 stable tag
         fetch-depth: 0
@@ -38,7 +38,7 @@ jobs:
     - name: Install toolchains
       run: |
         sudo apt-get update
-        sudo apt-get -y --no-install-recommends install gcc-12-multilib gcc-12-aarch64-linux-gnu gcc-12-arm-linux-gnueabi gcc-12-riscv64-linux-gnu nasm genisoimage uuid-dev
+        sudo apt-get -y --no-install-recommends install gcc-12-multilib gcc-12-aarch64-linux-gnu gcc-12-arm-linux-gnueabi gcc-12-riscv64-linux-gnu nasm genisoimage uuid-dev dosfstools mtools
         sudo ln -s /usr/bin/aarch64-linux-gnu-gcc-12 /usr/bin/aarch64-linux-gnu-gcc
         sudo ln -s /usr/bin/aarch64-linux-gnu-gcc-ar-12 /usr/bin/aarch64-linux-gnu-gcc-ar
         sudo ln -s /usr/bin/arm-linux-gnueabi-gcc-12 /usr/bin/arm-linux-gnueabi-gcc
@@ -101,12 +101,17 @@ jobs:
     - name: Create ISO filesystem structure
       run: |
         for BUILD_TYPE in ${{ env.BUILD_TYPES }}; do
-          mkdir -p $BUILD_TYPE/efi/boot
+          # Follow the casing convention of https://uefi.org/specs/UEFI/2.11/03_Boot_Manager.html#removable-media-boot-behavior
+          # which means uppercase for everything except the 'x' in 'BOOTx64.EFI'
+          mkdir -p $BUILD_TYPE/EFI/BOOT
           for ARCH in ${{ env.ARCHS }}; do
-            mv edk2/Build/Shell/${BUILD_TYPE}_${{ env.COMPILER }}/$ARCH/Shell_${{ env.FULL_SHELL_GUID }}.efi $BUILD_TYPE/efi/boot/boot${ARCH,,}.efi
+            mv edk2/Build/Shell/${BUILD_TYPE}_${{ env.COMPILER }}/$ARCH/Shell_${{ env.FULL_SHELL_GUID }}.efi $BUILD_TYPE/EFI/BOOT/BOOT$ARCH.EFI
           done
-          if [ -f $BUILD_TYPE/efi/boot/bootaarch64.efi ]; then
-            mv $BUILD_TYPE/efi/boot/bootaarch64.efi $BUILD_TYPE/efi/boot/bootaa64.efi
+          if [ -f $BUILD_TYPE/EFI/BOOT/BOOTAARCH64.EFI ]; then
+            mv $BUILD_TYPE/EFI/BOOT/BOOTAARCH64.EFI $BUILD_TYPE/EFI/BOOT/BOOTAA64.EFI
+          fi
+          if [ -f $BUILD_TYPE/EFI/BOOT/BOOTX64.EFI ]; then
+            mv $BUILD_TYPE/EFI/BOOT/BOOTX64.EFI $BUILD_TYPE/EFI/BOOT/BOOTx64.EFI
           fi
           printf "*** UEFI Shell v%s, release %s%s ***\n\n" ${{ steps.set_version.outputs.shell_version }} ${{ steps.set_version.outputs.shell_release }} "$( [ $BUILD_TYPE == DEBUG ] && echo ' (DEBUG BUILD)')" > $BUILD_TYPE/README.txt
           printf "This bootable image contains builds of the official UEFI Shell, as provided by\n" >> $BUILD_TYPE/README.txt
@@ -139,22 +144,34 @@ jobs:
           printf "</release>\n" >> Version.xml
         done
 
+    - name: Create the El-Torito FAT32 disk images
+      run: |
+        for BUILD_TYPE in ${{ env.BUILD_TYPES }}; do
+          # genisoimage requires the El-Torito images to be within the source directory folder even though they
+          # are completely independent of the ISO-9660 CD-ROM volumes (and not part of the visible file system),
+          # so we place them into a '[BOOT]/' subfolder that follows 7-zip's virtual image presentation logic.
+          mkdir "$BUILD_TYPE/[BOOT]"
+          dd if=/dev/zero of="$BUILD_TYPE/[BOOT]/Boot-NoEmul.img" bs=1M count=8
+          mkdosfs "$BUILD_TYPE/[BOOT]/Boot-NoEmul.img" -n "UEFI SHELL"
+          mcopy -s -i "$BUILD_TYPE/[BOOT]/Boot-NoEmul.img" $BUILD_TYPE/EFI/ ::
+        done
+
     - name: Generate ISO images
       run: |
         for BUILD_TYPE in ${{ env.BUILD_TYPES }}; do
-          genisoimage -v -V "UEFI SHELL ${{ steps.set_version.outputs.shell_version }} ${{ steps.set_version.outputs.shell_release }} ($BUILD_TYPE)" -JR -o "UEFI-Shell-${{ steps.set_version.outputs.shell_version }}-${{ steps.set_version.outputs.shell_release }}-$BUILD_TYPE.iso" $BUILD_TYPE
+          genisoimage -V "UEFI SHELL ${{ steps.set_version.outputs.shell_version }} ${{ steps.set_version.outputs.shell_release }} ($BUILD_TYPE)" -e "[BOOT]/Boot-NoEmul.img" -no-emul-boot -JR -o "UEFI-Shell-${{ steps.set_version.outputs.shell_version }}-${{ steps.set_version.outputs.shell_release }}-$BUILD_TYPE.iso" $BUILD_TYPE
         done
 
     - name: Display SHA-256
       run: |
         for BUILD_TYPE in ${{ env.BUILD_TYPES }}; do
-          sha256sum $BUILD_TYPE/efi/boot/*.efi
+          sha256sum $BUILD_TYPE/EFI/BOOT/*.EFI
         done
         sha256sum *.iso
         sha256sum *.efi
 
     - name: Upload ISO artifacts
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v5
       with:
         name: ISOs
         path: ./*.iso