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kconfig: Prune kconfig files that don't match the ARCH or BOARD

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When Kconfiglib was introduced it caused a significant performance
issue. This patch uses pruning to mitigate the performance issue.

The pruning exploits the fact that before the Kconfig database is
parsed we already know what ARCH and BOARD has been selected. So in
theory we could prune away all Kconfig sources that are not related to
the current ARCH or BOARD. In practice, it is only the Kconfig sources
in zephyr/arch/$ARCH and zephyr/board/$ARCH/ that are easy to prune.

Still, that is quite a few Kconfig sources. For qemu_x86 this patch
reduced the number of parsed Kconfig source files from 632 to
272. This pruning resulted in a incremental reconfiguration (time
cmake ..) speedup of 21% (0.56s to 0.46) and a clean build speedup of
4% (Using board qemu_x86 and sample hello_world).

Furthermore, it should be easier to maintain ARCH's and BOARD's
out-of-tree since the user now has a mechanism to redirect where
Kconfig sources are found. But this has not been explored.

Signed-off-by: Sebastian Bøe <sebastian.boe@nordicsemi.no>
This commit is contained in:
Sebastian Bøe 2018-01-09 14:12:07 +01:00 committed by Anas Nashif
parent a8b361b176
commit 4b61bd1b7a
4 changed files with 20 additions and 5 deletions
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12
Kconfig.zephyr
View file

@ -10,6 +10,14 @@ config KERNELVERSION
string
option env="KERNELVERSION"
config ENV_VAR_SYM_BOARD_DIR
string
option env="ENV_VAR_BOARD_DIR"
config ENV_VAR_SYM_ARCH
string
option env="ENV_VAR_ARCH"
source "arch/Kconfig"
source "kernel/Kconfig"
@ -37,5 +45,5 @@ source "tests/Kconfig"
# Board defaults should be parsed after SoC defaults
# because board usually overrides SoC values.
#
source "arch/*/soc/*/Kconfig.defconfig"
source "boards/*/*/Kconfig.defconfig"
source "arch/$ENV_VAR_SYM_ARCH/soc/*/Kconfig.defconfig"
source "$ENV_VAR_SYM_BOARD_DIR/Kconfig.defconfig"

2
arch/Kconfig
View file

@ -298,6 +298,6 @@ config BOARD
arch/<arch>/soc/<family>/<series>
source "arch/*/Kconfig"
source "arch/$ENV_VAR_SYM_ARCH/Kconfig"
source "boards/Kconfig"

4
boards/Kconfig
View file

@ -16,10 +16,10 @@ config QEMU_TARGET
choice
prompt "Board Selection"
source "boards/*/*/Kconfig.board"
source "$ENV_VAR_SYM_BOARD_DIR/Kconfig.board"
endchoice
menu "Board Options"
source "boards/*/*/Kconfig"
source "$ENV_VAR_SYM_BOARD_DIR/Kconfig"
endmenu

7
cmake/kconfig.cmake
View file

@ -33,6 +33,11 @@ set(COMMAND_FOR_menuconfig ${KCONFIG_MCONF} ${KCONFIG_ROOT})
set(COMMAND_FOR_oldconfig ${KCONFIG_CONF} --oldconfig ${KCONFIG_ROOT})
set(COMMAND_FOR_xconfig qconf ${KCONFIG_ROOT})
# Set environment variables so that Kconfig can prune Kconfig source
# files for other architectures
set(ENV{ENV_VAR_ARCH} ${ARCH})
set(ENV{ENV_VAR_BOARD_DIR} ${BOARD_DIR})
foreach(kconfig_target ${kconfig_target_list})
if (NOT WIN32)
add_custom_target(
@ -41,6 +46,8 @@ foreach(kconfig_target ${kconfig_target_list})
srctree=${PROJECT_SOURCE_DIR}
KERNELVERSION=${PROJECT_VERSION}
KCONFIG_CONFIG=${DOTCONFIG}
ENV_VAR_ARCH=$ENV{ENV_VAR_ARCH}
ENV_VAR_BOARD_DIR=$ENV{ENV_VAR_BOARD_DIR}
${COMMAND_FOR_${kconfig_target}}
WORKING_DIRECTORY ${PROJECT_BINARY_DIR}/kconfig
USES_TERMINAL