From 330bd380e8b691833c8dcc9b579b51851cbd4b0f Mon Sep 17 00:00:00 2001
From: Daniel Golle <daniel@makrotopia.org>
Date: Sun, 21 Feb 2021 14:19:26 +0000
Subject: image: allow building FIT and uImage with ramdisk

Instead of embedding the initrd cpio archive into the kernel, allow
for having an external ramdisk added to the FIT or uImage.
This is useful to overcome kernel size limitations present in many
stock bootloaders, as the ramdisk is then loaded seperately and doesn't
add to the kernel size. Hence we can have larger ramdisks to host ie.
installers with all binaries to flash included (or a web-based
firmware selector).
In terms of performance and total size the differences are neglectible.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
 include/image-commands.mk | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

(limited to 'include/image-commands.mk')

diff --git a/include/image-commands.mk b/include/image-commands.mk
index 3377680a07..d4ec51ca7c 100644
--- a/include/image-commands.mk
+++ b/include/image-commands.mk
@@ -196,11 +196,22 @@ define Build/eva-image
 	mv $@.new $@
 endef
 
+define Build/initrd_compression
+	$(if $(CONFIG_TARGET_INITRAMFS_COMPRESSION_BZIP2),.bzip2) \
+	$(if $(CONFIG_TARGET_INITRAMFS_COMPRESSION_GZIP),.gzip) \
+	$(if $(CONFIG_TARGET_INITRAMFS_COMPRESSION_LZMA),.lzma) \
+	$(if $(CONFIG_TARGET_INITRAMFS_COMPRESSION_XZ),.xz) \
+	$(if $(CONFIG_TARGET_INITRAMFS_COMPRESSION_ZSTD),.zstd)
+endef
+
 define Build/fit
 	$(TOPDIR)/scripts/mkits.sh \
 		-D $(DEVICE_NAME) -o $@.its -k $@ \
 		$(if $(word 2,$(1)),-d $(word 2,$(1))) -C $(word 1,$(1)) \
 		$(if $(findstring with-rootfs,$(word 3,$(1))),-r $(IMAGE_ROOTFS)) \
+		$(if $(findstring with-initrd,$(word 3,$(1))), \
+			$(if $(CONFIG_TARGET_ROOTFS_INITRAMFS_SEPERATE), \
+				-i $(KERNEL_BUILD_DIR)/initrd.cpio$(strip $(call Build/initrd_compression)))) \
 		-a $(KERNEL_LOADADDR) -e $(if $(KERNEL_ENTRY),$(KERNEL_ENTRY),$(KERNEL_LOADADDR)) \
 		$(if $(DEVICE_FDT_NUM),-n $(DEVICE_FDT_NUM)) \
 		-c $(if $(DEVICE_DTS_CONFIG),$(DEVICE_DTS_CONFIG),"config@1") \
@@ -450,6 +461,22 @@ define Build/uImage
 	mv $@.new $@
 endef
 
+define Build/uImage-with-ramdisk
+	mkimage \
+		-A $(LINUX_KARCH) \
+		-O linux \
+		-T kernel \
+		-C $(word 1,$(1)) \
+		-a $(KERNEL_LOADADDR) \
+		-e $(if $(KERNEL_ENTRY),$(KERNEL_ENTRY),$(KERNEL_LOADADDR)) \
+		-i $(KERNEL_BUILD_DIR)/initrd.cpio.$(strip $(call Build/initrd_compression)) \
+		-n '$(if $(UIMAGE_NAME),$(UIMAGE_NAME),$(call toupper,$(LINUX_KARCH)) $(VERSION_DIST) Linux-$(LINUX_VERSION))' \
+		$(if $(UIMAGE_MAGIC),-M $(UIMAGE_MAGIC)) \
+		$(wordlist 2,$(words $(1)),$(1)) \
+		-d $@ $@.new
+	mv $@.new $@
+endef
+
 define Build/xor-image
 	$(STAGING_DIR_HOST)/bin/xorimage -i $@ -o $@.xor $(1)
 	mv $@.xor $@
-- 
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