[coreboot-gerrit] Change in coreboot[master]: arch/x86: Add option to compress postcar stage

[Arthur Heymans (Code Review)]

Arthur Heymans has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/36674 )

Change subject: arch/x86: Add option to compress postcar stage
......................................................................

arch/x86: Add option to compress postcar stage

The LZ4 decompressor was already linked in romstage.

Change-Id: I89fdc6066027447bf72968c66e6f5eb5fbb630c7
Signed-off-by: Arthur Heymans 
---
M src/Kconfig
M src/arch/x86/Makefile.inc
2 files changed, 19 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/74/36674/1

diff --git a/src/Kconfig b/src/Kconfig
index 0d56291..17bf545 100644
--- a/src/Kconfig
+++ b/src/Kconfig
@@ -158,6 +158,16 @@
      that decompression might slow down booting if the boot flash
      is connected through a slow link (i.e. SPI).

+config COMPRESS_POSTCAR
+	bool "Compress postcar with LZ4"
+	depends on POSTCAR_STAGE
+	# Default value set at the end of the file
+	help
+	  Compress postcar with LZ4 to save flash space and speed up boot,
+	  since the time for reading the image from SPI (and in the vboot
+	  case verifying it) is usually much greater than the time spent
+	  decompressing.
+
 config COMPRESS_PRERAM_STAGES
    bool "Compress romstage and verstage with LZ4"
    depends on !ARCH_X86 && (HAVE_ROMSTAGE || HAVE_VERSTAGE)
@@ -1203,6 +1213,9 @@
 config COMPRESS_RAMSTAGE
    default y if !UNCOMPRESSED_RAMSTAGE

+config COMPRESS_POSTCAR
+	default y
+
 config COMPRESS_PRERAM_STAGES
    depends on !ARCH_X86
    default y
diff --git a/src/arch/x86/Makefile.inc b/src/arch/x86/Makefile.inc
index 447fd57..8c35176 100644
--- a/src/arch/x86/Makefile.inc
+++ b/src/arch/x86/Makefile.inc
@@ -278,11 +278,16 @@
 $(objcbfs)/postcar.elf: $(objcbfs)/postcar.debug.rmod
    cp $< $@

+CBFS_POSTCAR_COMPRESS_FLAG := none
+ifeq ($(CONFIG_COMPRESS_POSTCAR),y)
+CBFS_POSTCAR_COMPRESS_FLAG := lz4
+endif
+
 # Add postcar to CBFS
 cbfs-files-$(CONFIG_POSTCAR_STAGE)  += $(CONFIG_CBFS_PREFIX)/postcar
 $(CONFIG_CBFS_PREFIX)/postcar-file := $(objcbfs)/postcar.elf
 $(CONFIG_CBFS_PREFIX)/postcar-type := stage
-$(CONFIG_CBFS_PREFIX)/postcar-compression := none
+$(CONFIG_CBFS_PREFIX)/postcar-compression := $(CBFS_POSTCAR_COMPRESS_FLAG)

###############################################################################
 # ramstage