Fix generating a boot image for grub-efi with mkisofs

A boot ISO image for grub-efi is currently generated using the
genisoimage-specific option '--efi-boot <grub_image>'. This is accepted
by genisoimage and 'xorriso -as genisoimage' but not by mkisofs:
> /usr/bin/mkisofs -J -r -input-charset utf-8 -V HelenOS-CD --efi-boot boot/grub/efi.img -o boot/grub/image.iso boot/grub/grub_dist
> Bad Option '--efi-boot' (error -1 BADFLAG).

When mkisofs is selected during the configure time, run the build
command with the equivalent options '-eltorito-platform efi
-eltorito-boot <grub_image> -no-emul-boot'.

Author: petrpavlu

boot/grub/meson.build

@@ -107,7 +107,11 @@ grub_image = 'boot/grub' / GRUB_ARCH + '.img'
 if GRUB_ARCH == 'pc'
 	genisoimage_args = [ '-eltorito-boot', grub_image, '-no-emul-boot', '-boot-info-table' ]
 elif GRUB_ARCH == 'efi'
-	genisoimage_args = [ '--efi-boot', grub_image ]
+	if genisoimage_type == 'mkisofs'
+		genisoimage_args = [ '-eltorito-platform', 'efi', '-eltorito-boot', grub_image, '-no-emul-boot' ]
+	else
+		genisoimage_args = [ '--efi-boot', grub_image ]
+	endif
 endif
 
 image_iso = custom_target('image.iso',

meson/part/tools/meson.build

@@ -61,18 +61,20 @@ if debug_shell_scripts
 endif
 
 genisoimage = find_program('genisoimage', required: false)
-
-if not genisoimage.found()
+if genisoimage.found()
+	genisoimage_type = 'genisoimage'
+else
 	genisoimage = find_program('mkisofs', required: false)
-endif
-
-if not genisoimage.found()
-	xorriso = find_program('xorriso', required: false)
-
-	if xorriso.found()
-		genisoimage = [ xorriso, '-as', 'genisoimage' ]
+	if genisoimage.found()
+		genisoimage_type = 'mkisofs'
 	else
-		error('Need genisoimage, mkisofs or xorriso.')
+		xorriso = find_program('xorriso', required: false)
+		if xorriso.found()
+			genisoimage = [ xorriso, '-as', 'genisoimage' ]
+			genisoimage_type = 'genisoimage'
+		else
+			error('Need genisoimage, mkisofs or xorriso.')
+		endif
 	endif
 endif