arm64: boot: add zstd support

Support build the zstd compressed Image.zst. Similar as other
compressed formats, the Image.zst is not self-decompressing and
the bootloader still needs to handle decompression before
launching the kernel image.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Link: https://lore.kernel.org/r/20220619170657.2657-1-jszhang@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/arch/arm64/boot/Makefile b/arch/arm64/boot/Makefile
index ebe80fa..a0e3ded 100644 (file)
--- a/arch/arm64/boot/Makefile
+++ b/arch/arm64/boot/Makefile
@@ -16,7 +16,7 @@
 
 OBJCOPYFLAGS_Image :=-O binary -R .note -R .note.gnu.build-id -R .comment -S
 
-targets := Image Image.bz2 Image.gz Image.lz4 Image.lzma Image.lzo
+targets := Image Image.bz2 Image.gz Image.lz4 Image.lzma Image.lzo Image.zst
 
 $(obj)/Image: vmlinux FORCE
        $(call if_changed,objcopy)
@@ -35,3 +35,6 @@ $(obj)/Image.lzma: $(obj)/Image FORCE
 
 $(obj)/Image.lzo: $(obj)/Image FORCE
        $(call if_changed,lzo)
+
+$(obj)/Image.zst: $(obj)/Image FORCE
+       $(call if_changed,zstd)