bootimage.bbclass, grub-efi.bbclass: Improve EFI & PCBIOS+EFI ISO support

Using the latest mkisofs it is possible to generate 3 different types
of ISO images, which can be used in various scenarios.

1) PCBIOS Only ISO
   - This option remains unchanged by this commit
   - Uses syslinux menus
   - Can be directly copied with dd to a USB device
   - Can be burned to optical media

2) EFI Only ISO
   - Uses grub 2 menus
   - Can be burned to optical media
   - If you want to use this image on a USB device
     extra steps must be taken in order to format the USB
     device with fat32, and copy an EFI loader which will
     in turn load the iso image

3) PCBIOS / EFI ISO
   - This is a hybrid image ISO that will work for case 1 or 2
     as above with the same restrictions and boot menu types
     depending on what type of firmware is installed on
     the hardware or depending on if EFI or "Legacy Boot" is
     enabled on some UEFI firmwares.

The syslinux.bbclass is now always required because that is where the
isohybrid dependencies come from as well as the configuration data for
the isohybrid.  The isohybrid is the secret sauce which allows the ISO
to work as optical media or as a disk image on USB or a HDD/SSD.

[YOCTO #4100]

(From OE-Core rev: a4baf911ab9d306ce5200e7d794ed6a9ccb25f30)

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/bootimg.bbclass

@@ -32,6 +32,7 @@ EXCLUDE_FROM_WORLD = "1"
 
 HDDDIR = "${S}/hddimg"
 ISODIR = "${S}/iso"
+EFIIMGDIR = "${S}/efi_img"
 
 BOOTIMG_VOLUME_ID   ?= "boot"
 BOOTIMG_EXTRA_SPACE ?= "512"
@@ -48,15 +49,10 @@ def pcbios(d):
         pcbios = base_contains("MACHINE_FEATURES", "efi", "0", "1", d)
     return pcbios
 
-def pcbios_class(d):
-    if d.getVar("PCBIOS", True) == "1":
-        return "syslinux"
-    return ""
-
 PCBIOS = "${@pcbios(d)}"
-PCBIOS_CLASS = "${@pcbios_class(d)}"
 
-inherit ${PCBIOS_CLASS}
+# The syslinux is required for the isohybrid command and boot catalog
+inherit syslinux
 inherit ${EFI_CLASS}
 
 populate() {
@@ -90,21 +86,36 @@ build_iso() {
 	fi
 	if [ "${EFI}" = "1" ]; then
 		grubefi_iso_populate
+		build_fat_img ${EFIIMGDIR} ${ISODIR}/efi.img
 	fi
 
-	if [ "${PCBIOS}" = "1" ]; then
+	# EFI only
+	if [ "${PCBIOS}" != "1" ] && [ "${EFI}" = "1" ] ; then
+		# Work around bug in isohybrid where it requires isolinux.bin
+		# In the boot catalog, even though it is not used
+		mkdir -p ${ISODIR}/${ISOLINUXDIR}
+		install -m 0644 ${STAGING_DATADIR}/syslinux/isolinux.bin ${ISODIR}${ISOLINUXDIR}
+	fi
+
+	if [ "${PCBIOS}" = "1" ] && [ "${EFI}" != "1" ] ; then
+		# PCBIOS only media
 		mkisofs -V ${BOOTIMG_VOLUME_ID} \
 		        -o ${DEPLOY_DIR_IMAGE}/${IMAGE_NAME}.iso \
 			-b ${ISO_BOOTIMG} -c ${ISO_BOOTCAT} -r \
 			${MKISOFS_OPTIONS} ${ISODIR}
 	else
-		bbnote "EFI-only ISO images are untested, please provide feedback."
-		mkisofs -V ${BOOTIMG_VOLUME_ID} \
+		# EFI only OR EFI+PCBIOS
+		mkisofs -A ${BOOTIMG_VOLUME_ID} -V ${BOOTIMG_VOLUME_ID} \
 		        -o ${DEPLOY_DIR_IMAGE}/${IMAGE_NAME}.iso \
-			-r ${ISODIR}
+			-b ${ISO_BOOTIMG} -c ${ISO_BOOTCAT} \
+			-r ${MKISOFS_OPTIONS} \
+			-eltorito-alt-boot -eltorito-platform efi \
+			-b efi.img -no-emul-boot \
+			${ISODIR}
+		isohybrid_args="-u"
 	fi
 
-	isohybrid ${DEPLOY_DIR_IMAGE}/${IMAGE_NAME}.iso
+	isohybrid $isohybrid_args ${DEPLOY_DIR_IMAGE}/${IMAGE_NAME}.iso
 
 	cd ${DEPLOY_DIR_IMAGE}
 	rm -f ${DEPLOY_DIR_IMAGE}/${IMAGE_LINK_NAME}.iso

meta/classes/grub-efi.bbclass

@@ -41,6 +41,14 @@ grubefi_populate() {
 
 grubefi_iso_populate() {
 	grubefi_populate ${ISODIR}
+	# Build a EFI directory to create efi.img
+	mkdir -p ${EFIIMGDIR}/${EFIDIR}
+	cp ${ISODIR}/${EFIDIR}/* ${EFIIMGDIR}${EFIDIR}
+	cp ${ISODIR}/vmlinuz ${EFIIMGDIR}
+	echo "EFI\\BOOT\\${GRUB_IMAGE}" > ${EFIIMGDIR}/startup.nsh
+	if [ -f "${ISODIR}/initrd" ] ; then
+		cp ${ISODIR}/initrd ${EFIIMGDIR}
+	fi
 }
 
 grubefi_hddimg_populate() {