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authorBertrand Jacquin <beber@meleeweb.net>2014-08-27 20:31:56 +0930
committerRusty Russell <rusty@rustcorp.com.au>2014-08-27 21:54:12 +0930
commitbeb50df39e91745604ce3cb9dc6a503f39f4383d (patch)
treeeaa6a996228eb532f56f46d1b5004a10062ac4fa /init/Kconfig
parent40e42f6a2596bbe757e561d4806fadd924f8c9fd (diff)
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kbuild: handle module compression while running 'make modules_install'.
Since module-init-tools (gzip) and kmod (gzip and xz) support compressed modules, it could be useful to include a support for compressing modules right after having them installed. Doing this in kbuild instead of per distro can permit to make this kind of usage more generic. This patch add a Kconfig entry to "Enable loadable module support" menu and let you choose to compress using gzip (default) or xz. Both gzip and xz does not used any extra -[1-9] option since Andi Kleen and Rusty Russell prove no gain is made using them. gzip is called with -n argument to avoid storing original filename inside compressed file, that way we can save some more bytes. On a v3.16 kernel, 'make allmodconfig' generated 4680 modules for a total of 378MB (no strip, no sign, no compress), the following table shows observed disk space gain based on the allmodconfig .config : | time | +-------------+-----------------+ | manual .ko | make | size | percent | compression | modules_install | | gain +-------------+-----------------+------+-------- - | | 18.61s | 378M | GZIP | 3m16s | 3m37s | 102M | 73.41% XZ | 5m22s | 5m39s | 77M | 79.83% The gain for restricted environnement seems to be interesting while uncompress can be time consuming but happens only while loading a module, that is generally done only once. This is fully compatible with signed modules while the signed module is compressed. module-init-tools or kmod handles decompression and provide to other layer the uncompressed but signed payload. Reviewed-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Bertrand Jacquin <beber@meleeweb.net> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'init/Kconfig')
-rw-r--r--init/Kconfig43
1 files changed, 43 insertions, 0 deletions
diff --git a/init/Kconfig b/init/Kconfig
index e84c6423a2e5..4980925bf348 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1906,6 +1906,49 @@ config MODULE_SIG_HASH
default "sha384" if MODULE_SIG_SHA384
default "sha512" if MODULE_SIG_SHA512
+config MODULE_COMPRESS
+ bool "Compress modules on installation"
+ depends on MODULES
+ help
+ This option compresses the kernel modules when 'make
+ modules_install' is run.
+
+ The modules will be compressed either using gzip or xz depend on the
+ choice made in "Compression algorithm".
+
+ module-init-tools has support for gzip format while kmod handle gzip
+ and xz compressed modules.
+
+ When a kernel module is installed from outside of the main kernel
+ source and uses the Kbuild system for installing modules then that
+ kernel module will also be compressed when it is installed.
+
+ This option provides little benefit when the modules are to be used inside
+ an initrd or initramfs, it generally is more efficient to compress the whole
+ initrd or initramfs instead.
+
+ This is fully compatible with signed modules while the signed module is
+ compressed. module-init-tools or kmod handles decompression and provide to
+ other layer the uncompressed but signed payload.
+
+choice
+ prompt "Compression algorithm"
+ depends on MODULE_COMPRESS
+ default MODULE_COMPRESS_GZIP
+ help
+ This determines which sort of compression will be used during
+ 'make modules_install'.
+
+ GZIP (default) and XZ are supported.
+
+config MODULE_COMPRESS_GZIP
+ bool "GZIP"
+
+config MODULE_COMPRESS_XZ
+ bool "XZ"
+
+endchoice
+
endif # MODULES
config INIT_ALL_POSSIBLE