[1/2] kbuild: allow setting zstd compression level for modules

Commit Message

Tor Vic April 9, 2021, 1:28 p.m. UTC

Zstd offers a very fine-grained control of compression ratios.
Add a Kconfig option that allows setting the desired compression
level for module compression.

Based on Masahiro's linux-kbuild.

Signed-off-by: Tor Vic <[e-mail]>
Tested-by: Piotr Gorski <[e-mail]>
---
 init/Kconfig             | 8 ++++++++
 scripts/Makefile.modinst | 2 +-
 2 files changed, 9 insertions(+), 1 deletion(-)

Patch

diff --git a/init/Kconfig b/init/Kconfig
index b5744d32c..15bb02c24 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -2275,6 +2275,14 @@  config MODULE_COMPRESS_ZSTD
 
 endchoice
 
+config MODULE_COMPRESS_ZSTD_LEVEL
+    int "Compression level (1-19)"
+    depends on MODULE_COMPRESS_ZSTD
+    range 1 19
+    default 3
+    help
+        Compression level used by zstd for compressing modules.
+
 config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
 	bool "Allow loading of modules with missing namespace imports"
 	help
diff --git a/scripts/Makefile.modinst b/scripts/Makefile.modinst
index ff9b09e4c..0a0db2278 100644
--- a/scripts/Makefile.modinst
+++ b/scripts/Makefile.modinst
@@ -97,7 +97,7 @@  quiet_cmd_gzip = GZIP    $@
 quiet_cmd_xz = XZ      $@
       cmd_xz = $(XZ) --lzma2=dict=2MiB -f $<
 quiet_cmd_zstd = ZSTD    $@
-      cmd_zstd = $(ZSTD) -T0 --rm -f -q $<
+      cmd_zstd = $(ZSTD) -$(CONFIG_MODULE_COMPRESS_ZSTD_LEVEL) -T0 --rm -f -q $<
 
 $(dst)/%.ko.gz: $(dst)/%.ko FORCE
 	$(call cmd,gzip)