[M] Change in coreboot[master]: Kconfig: Add option to compress ramstage with LZ4

[Martin L Roth (Code Review)]

Martin L Roth has submitted this change. ( https://review.coreboot.org/c/coreboot/+/71673 )

Change subject: Kconfig: Add option to compress ramstage with LZ4
......................................................................

Kconfig: Add option to compress ramstage with LZ4

When ramstage is loaded asynchronously, as on the skyrim boards, the
faster decompression of LZ4 allows for faster boot times than the
tighter compression of LZMA.

To make this change, the name of the existing ramstage_compression
option needs to be updated.

BUG=b:264409477
TEST=Boot skyrim, look at boot speed

Signed-off-by: Martin Roth 
Change-Id: I27dd1a8def024e0efd466cef9ffd9ca71717486a
Reviewed-on: https://review.coreboot.org/c/coreboot/+/71673
Reviewed-by: Fred Reitberger 
Tested-by: build bot (Jenkins) 
---
M Makefile.inc
M src/Kconfig
M src/lib/Makefile.inc
M src/lib/cbfs.c
4 files changed, 59 insertions(+), 12 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Fred Reitberger: Looks good to me, approved

diff --git a/Makefile.inc b/Makefile.inc
index 5cd13ba..2b5d742 100644
--- a/Makefile.inc
+++ b/Makefile.inc
@@ -372,9 +372,12 @@
 #######################################################################
 # a variety of flags for our build
 CBFS_COMPRESS_FLAG:=none
-ifeq ($(CONFIG_COMPRESS_RAMSTAGE),y)
+ifeq ($(CONFIG_COMPRESS_RAMSTAGE_LZMA),y)
 CBFS_COMPRESS_FLAG:=LZMA
 endif
+ifeq ($(CONFIG_COMPRESS_RAMSTAGE_LZ4),y)
+CBFS_COMPRESS_FLAG:=LZ4
+endif

CBFS_PAYLOAD_COMPRESS_FLAG:=none
 ifeq ($(CONFIG_COMPRESSED_PAYLOAD_LZMA),y)
diff --git a/src/Kconfig b/src/Kconfig
index f68553c..8246a17 100644
--- a/src/Kconfig
+++ b/src/Kconfig
@@ -170,12 +170,36 @@
      every boot.  Use this if you want the NVRAM configuration to
      never be modified from its default values.

-config COMPRESS_RAMSTAGE
-	bool "Compress ramstage with LZMA"
-	depends on HAVE_RAMSTAGE
-	# Default value set at the end of the file
+config MB_COMPRESS_RAMSTAGE_LZ4
+	bool
    help
-	  Compress ramstage to save memory in the flash image.
+	  Select this in a mainboard to use LZ4 compression by default
+
+choice
+	prompt "Ramstage compression"
+	depends on HAVE_RAMSTAGE && !UNCOMPRESSED_RAMSTAGE
+	default COMPRESS_RAMSTAGE_LZ4 if MB_COMPRESS_RAMSTAGE_LZ4
+	default COMPRESS_RAMSTAGE_LZMA
+
+config COMPRESS_RAMSTAGE_LZMA
+	bool "Compress ramstage with LZMA"
+	help
+	  Compress ramstage with LZMA to save memory in the flash image.
+
+config COMPRESS_RAMSTAGE_LZ4
+	bool "Compress ramstage with LZ4"
+	help
+	  LZ4 doesn't give as good compression as LZMA, but decompresses much
+	  faster. For large binaries such as ramstage, it's typically best to
+	  use LZMA, but there can be cases where the faster decompression of
+	  LZ4 can lead to a faster boot time. Testing on each individual board
+	  is typically going to be needed due to the large number of factors
+	  that can influence the decision. Binary size, CPU speed, ROM read
+	  speed, cache, and other factors all play a part.
+
+	  If you're not sure, stick with LZMA.
+
+endchoice

config COMPRESS_PRERAM_STAGES
    bool "Compress romstage and verstage with LZ4"
@@ -1379,9 +1403,6 @@
 # Set default values for symbols created before mainboards.  This allows the
 # option to be displayed in the general menu, but the default to be loaded in
 # the mainboard if desired.
-config COMPRESS_RAMSTAGE
-	default y if !UNCOMPRESSED_RAMSTAGE
-
 config COMPRESS_PRERAM_STAGES
    depends on (HAVE_ROMSTAGE || HAVE_VERSTAGE) && NO_XIP_EARLY_STAGES
    default y
diff --git a/src/lib/Makefile.inc b/src/lib/Makefile.inc
index dcba0c6..030959c 100644
--- a/src/lib/Makefile.inc
+++ b/src/lib/Makefile.inc
@@ -95,7 +95,7 @@
 romstage-y += fmap.c
 romstage-y += delay.c
 romstage-y += cbfs.c
-romstage-$(CONFIG_COMPRESS_RAMSTAGE) += lzma.c lzmadecode.c
+romstage-$(CONFIG_COMPRESS_RAMSTAGE_LZMA) += lzma.c lzmadecode.c
 romstage-y += libgcc.c
 romstage-y += memrange.c
 romstage-$(CONFIG_PRIMITIVE_MEMTEST) += primitive_memtest.c
@@ -294,7 +294,7 @@
 postcar-y += gcc.c
 postcar-y += halt.c
 postcar-y += libgcc.c
-postcar-$(CONFIG_COMPRESS_RAMSTAGE) += lzma.c lzmadecode.c
+postcar-$(CONFIG_COMPRESS_RAMSTAGE_LZMA) += lzma.c lzmadecode.c
 postcar-y += memchr.c
 postcar-y += memcmp.c
 postcar-y += prog_loaders.c
diff --git a/src/lib/cbfs.c b/src/lib/cbfs.c
index d2829d1..0b2d66b 100644
--- a/src/lib/cbfs.c
+++ b/src/lib/cbfs.c
@@ -142,7 +142,7 @@
    	return false;
    if (ENV_ROMSTAGE && CONFIG(POSTCAR_STAGE))
    	return false;
-	if ((ENV_ROMSTAGE || ENV_POSTCAR) && !CONFIG(COMPRESS_RAMSTAGE))
+	if ((ENV_ROMSTAGE || ENV_POSTCAR) && !CONFIG(COMPRESS_RAMSTAGE_LZMA))
    	return false;
    if (ENV_SMM)
    	return false;