RISC-V: Build flat and compressed kernel images

This patch extends Linux RISC-V build system to build and install:
Image - Flat uncompressed kernel image
Image.gz - Flat and GZip compressed kernel image

Quiet a few bootloaders (such as Uboot, UEFI, etc) are capable of
booting flat and compressed kernel images. In case of Uboot, booting
Image or Image.gz is achieved using bootm command.

The flat and uncompressed kernel image (i.e. Image) is very useful
in pre-silicon developent and testing because we can create back-door
HEX files for RAM on FPGAs from Image.

Signed-off-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

1 files changed, 14 insertions, 1 deletions

diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index 4af153a182b0..4b594f2e4f7e 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -71,6 +71,10 @@ KBUILD_CFLAGS += $(call cc-option,-mstrict-align)
 # arch specific predefines for sparse
 CHECKFLAGS += -D__riscv -D__riscv_xlen=$(BITS)
 
+# Default target when executing plain make
+boot		:= arch/riscv/boot
+KBUILD_IMAGE	:= $(boot)/Image.gz
+
 head-y := arch/riscv/kernel/head.o
 
 core-y += arch/riscv/kernel/ arch/riscv/mm/
@@ -81,4 +85,13 @@ PHONY += vdso_install
 vdso_install:
 	$(Q)$(MAKE) $(build)=arch/riscv/kernel/vdso $@
 
-all: vmlinux
+all: Image.gz
+
+Image: vmlinux
+	$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
+
+Image.%: Image
+	$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
+
+zinstall install:
+	$(Q)$(MAKE) $(build)=$(boot) $@