build: centralize fakeroot code

This patch moves the fakeroot code required by some devices to
`image-commands.mk`.

Create the fakeroot on the fly by using the undocumented -s (skip copy)
parameter of mkimage.

Signed-off-by: Joseph C. Lehner <joseph.c.lehner@gmail.com>
[remove unused NETGEAR_KERNEL_MAGIC, remove workarounds to have a dummy
rootfs for mkimage]
Signed-off-by: Mathias Kresin <dev@kresin.me>

include/image-commands.mk

@@ -62,6 +62,18 @@ define Build/netgear-dni
 	mv $@.new $@
 endef
 
+# append a fake/empty rootfs uImage header, to fool the bootloaders
+# rootfs integrity check
+define Build/append-uImage-fakeroot-hdr
+	rm -f $@.fakeroot
+	$(STAGING_DIR_HOST)/bin/mkimage \
+		-A $(LINUX_KARCH) -O linux -T filesystem -C none \
+		-n '$(call toupper,$(LINUX_KARCH)) LEDE fakeroot' \
+		-s \
+		$@.fakeroot
+	cat $@.fakeroot >> $@
+endef
+
 define Build/tplink-safeloader
        -$(STAGING_DIR_HOST)/bin/tplink-safeloader \
 		-B $(TPLINK_BOARD_NAME) \
@@ -143,10 +155,6 @@ define Build/append-rootfs
 	dd if=$(IMAGE_ROOTFS) >> $@
 endef
 
-define Build/append-file
-	cat "$(1)" >> "$@"
-endef
-
 define Build/append-ubi
 	sh $(TOPDIR)/scripts/ubinize-image.sh \
 		$(if $(UBOOTENV_IN_UBI),--uboot-env) \

target/linux/apm821xx/image/Makefile

@@ -129,23 +129,6 @@ define Build/create-uImage-dtb
 	@mv $@.new $@
 endef
 
-define Build/append-fakerootfs
-	rm -rf $@.fakerootsquashfs $@.fakefs
-
-	# append a fake/empty rootfs to fool netgear's uboot
-	# CHECK_DNI_FIRMWARE_ROOTFS_INTEGRITY in do_chk_dniimg()
-	dd if=/dev/zero of=$@.fakerd bs=16 count=1 conv=sync
-
-	-$(STAGING_DIR_HOST)/bin/mkimage \
-		-A $(LINUX_KARCH) -O linux -T filesystem -C none \
-		-a 0x00000000 -e 0x00000000 \
-		-n '$(DEVICE_PROFILE) fakerootfs' \
-		-d $@.fakerd $@.fakefs
-
-	cat $@.fakefs >> $@
-	rm -rf $@.fakerootsquashfs $@.fakefs
-endef
-
 define Build/wndr4700-specialImage
 	rm -rf $@.fakerd $@.new
 
@@ -192,7 +175,8 @@ define Device/WNDR4700
   IMAGE_SIZE := 24960k
   IMAGES := factory.img sysupgrade.tar kernel.dtb
   KERNEL_SIZE := 1920k
-  KERNEL := dtb | kernel-bin | lzma | uImage lzma | pad-offset $$(BLOCKSIZE) 64 | append-fakerootfs
+  KERNEL := dtb | kernel-bin | lzma | uImage lzma | pad-offset $$(BLOCKSIZE) 64 | \
+	  append-uImage-fakeroot-hdr
   KERNEL_INITRAMFS := kernel-bin | gzip | dtb | wndr4700-specialImage gzip
   IMAGE/factory.img := create-uImage-dtb | append-kernel | pad-to 2M | append-ubi | \
 		       netgear-dni | check-size $$$$(IMAGE_SIZE)

target/linux/ipq806x/image/Makefile

@@ -9,12 +9,6 @@ KERNEL_LOADADDR := 0x42208000
 
 define Image/Prepare
 	$(CP) $(LINUX_DIR)/vmlinux $(KDIR)/$(IMG_PREFIX)-vmlinux.elf
-	mkimage -A arm -O linux -T filesystem -C none \
-		-a $(KERNEL_LOADADDR) -e $(KERNEL_LOADADDR) \
-		-n 'ARM OpenWrt fakeroot' \
-		-s $(KDIR_TMP)/root.dummy-uImage.tmp
-	echo -ne '\xff' > $(KDIR_TMP)/root.dummy
-	cat $(KDIR_TMP)/root.dummy $(KDIR_TMP)/root.dummy-uImage.tmp > $(KDIR)/root.dummy
 endef
 
 define Image/BuildKernel
@@ -64,7 +58,8 @@ define Device/DniImage
 	FILESYSTEMS := squashfs
 	KERNEL_SUFFIX := -uImage
 	KERNEL_INITRAMFS := kernel-bin | append-dtb | uImage none
-	KERNEL = kernel-bin | append-dtb | pad-to $$$$(($$(KERNEL_SIZE)-2*64-1)) | uImage none | append-file $(KDIR)/root.dummy
+	KERNEL = kernel-bin | append-dtb | uImage none | pad-offset $$(KERNEL_SIZE) 64 | \
+		append-uImage-fakeroot-hdr
 	KERNEL_NAME := zImage
 	NETGEAR_BOARD_ID :=
 	NETGEAR_HW_ID :=
@@ -161,7 +156,7 @@ define Device/EA8500
 	BLOCKSIZE := 128k
 	KERNEL_SIZE := 3072k
 	FILESYSTEMS := squashfs
-	KERNEL = kernel-bin | append-dtb | uImage none | append-file $(KDIR)/root.dummy
+	KERNEL = kernel-bin | append-dtb | uImage none | append-uImage-fakeroot-hdr
 	PROFILES += $$(DEVICE_NAME)
 	BOARD_NAME := ea8500
 	UBINIZE_OPTS := -E 5

target/linux/ramips/image/mt7620.mk

@@ -58,7 +58,7 @@ define Device/ex2700
   BLOCKSIZE := 4k
   IMAGE_SIZE := $(ralink_default_fw_size_4M)
   IMAGES += factory.bin
-  KERNEL := $(KERNEL_DTB) | uImage lzma | pad-offset 64k 64 | append-file netgear-fake-uImage-hdr.bin
+  KERNEL := $(KERNEL_DTB) | uImage lzma | pad-offset 64k 64 | append-uImage-fakeroot-hdr
   IMAGE/factory.bin := $$(sysupgrade_bin) | check-size $$$$(IMAGE_SIZE) | \
 	netgear-dni
   DEVICE_TITLE := Netgear EX2700
@@ -71,7 +71,7 @@ define Device/wn3000rpv3
   DTS := WN3000RPV3
   BLOCKSIZE := 4k
   IMAGES += factory.bin
-  KERNEL := $(KERNEL_DTB) | uImage lzma | pad-offset 64k 64 | append-file netgear-fake-uImage-hdr.bin
+  KERNEL := $(KERNEL_DTB) | uImage lzma | pad-offset 64k 64 | append-uImage-fakeroot-hdr
   IMAGE/factory.bin := $$(sysupgrade_bin) | check-size $$$$(IMAGE_SIZE) | \
 	netgear-dni
   DEVICE_TITLE := Netgear WN3000RPv3