boot.mk, grub, syslinux: Add the ability to override BOOTLOADER

features.in/grub/config.mk

@@ -9,7 +9,6 @@ ifeq (,$(filter-out i586 x86_64,$(ARCH)))
 	@$(call try,BOOTVGA,normal)
 endif
 	@$(call set,RELNAME,ALT ($(IMAGE_NAME)))
-	@$(call set,IMAGE_PACKTYPE,boot)
 
 # UI is overwritten
 use/grub/ui/%: use/grub

features.in/syslinux/config.mk

@@ -8,7 +8,6 @@ use/syslinux: sub/stage1 $(ISOHYBRID:%=use/isohybrid)
 	@$(call add,SYSLINUX_FILES,/usr/lib/syslinux/pxelinux.0)
 	@$(call try,META_SYSTEM_ID,SYSLINUX)
 	@$(call set,RELNAME,ALT ($(IMAGE_NAME)))
-	@$(call set,IMAGE_PACKTYPE,boot)
 	@$(call xport,SYSLINUX_DEFAULT)
 else
 use/syslinux: ; @:

lib/boot.mk

@@ -4,28 +4,20 @@ endif
 
 ifeq (distro,$(IMAGE_CLASS))
 
-# install x86 media bootloader
+# install media bootloader
+boot/iso:
+	@$(call try,IMAGE_PACKTYPE,boot)
 ifeq (,$(filter-out i586 x86_64,$(ARCH)))
-boot/iso: use/syslinux
-	@$(call set,BOOTLOADER,isolinux)
+	@$(call try,BOOTLOADER,isolinux)
 endif
-
-# install aarch64 media bootloader
 ifeq (,$(filter-out aarch64,$(ARCH)))
-boot/iso:
-	@$(call set,BOOTLOADER,efiboot)
+	@$(call try,BOOTLOADER,efiboot)
 endif
-
-# firmware is the bootloader
 ifeq (,$(filter-out e2k%,$(ARCH)))
-boot/iso:
-	@$(call set,BOOTLOADER,e2k-boot)
+	@$(call try,BOOTLOADER,e2k-boot)
 endif
-
-# install bootloader for Open Boot (IEEE1275)
 ifeq (,$(filter-out ppc64le,$(ARCH)))
-boot/iso:
-	@$(call set,BOOTLOADER,ieee1275boot)
+	@$(call try,BOOTLOADER,ieee1275boot)
 endif
 
 endif