From: Simon Glass <sjg@chromium.org>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH v2 4/4] kbuild: improve Kbuild speed
Date: Sat, 1 Mar 2014 17:00:18 -0700 [thread overview]
Message-ID: <CAPnjgZ06EywQPaSCsXLjveZc2sT99xitXBWNRv_-j_cnnq6sPA@mail.gmail.com> (raw)
In-Reply-To: <1393561421-31785-5-git-send-email-yamada.m@jp.panasonic.com>
On 27 February 2014 21:23, Masahiro Yamada <yamada.m@jp.panasonic.com>wrote:
> Kbuild brought about many advantages for us but a significant
> performance regression was reported by Simon Glass.
>
> After some discussions and analysis, it turned out
> its main cause is in $(call cc-option,...).
>
> Historically, U-Boot parses all config.mk
> (arch/*/config.mk and board/*/config.mk)
> every time descending into subdirectories.
> That means cc-options are evaluated over and over again.
>
> $(call cc-option,...) is useful but costly.
> So we want to evaluate them only in ./Makefile
> and spl/Makefile and export compiler flags.
>
> This commit changes the build system as follows:
>
> - Modify scripts/Makefile.build to not include config.mk
> Instead, add $(PLATFORM_CPPFLAGS) to asflags-y, ccflags-y,
> cppflags-y.
>
> - Export many variables
> Going forward, Kbuild will not parse config.mk files
> when it descends into subdirectories.
> If we want to set variables in config.mk and use them
> in subdirectories, they must be exported.
>
> This is the list of variables to get exported:
> PLATFORM_CPPFLAGS
> CPUDIR
> BOARDDIR
> OBJCOPYFLAGS
> LDFLAGS
> LDFLAGS_FINAL
> (used in nand_spl/board/*/*/Makefile)
> CONFIG_STANDALONE_LOAD_ADDR
> (used in examples/standalone/Makefile)
> SYM_PREFIX
> (used in examples/standalone/Makefile)
> RELFLAGS
> (used in examples/standalone/Makefile)
>
> - Delete CPPFLAGS
> This variable has been replaced with PLATFORM_CPPFLAGS
>
> - Copy gcclibdir from example/standalone/Makefile
> to arch/sparc/config.mk
> The reference in CONFIG_STANDALONE_LOAD_ADDR must be
> resolved before it is exported.
>
> Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
> Reported-by: Simon Glass <sjg@chromium.org>
> Tested-by: Stephen Warren <swarren@nvidia.com>
>
Acked-by: Simon Glass <sjg@chromium.org>
Tested only on sandbox:
Tested-by: Simon Glass <sjg@chromium.org>
prev parent reply other threads:[~2014-03-02 0:00 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-28 4:23 [U-Boot] [PATCH v2 0/4] Big acceleration of Kbuild performance Masahiro Yamada
2014-02-28 4:23 ` [U-Boot] [PATCH v2 1/4] kbuild, blackfin: Add CONFIG_CC_OPTIMIZE_LIBS_FOR_SPEED Masahiro Yamada
2014-02-28 4:23 ` [U-Boot] [PATCH v2 2/4] kbuild: add CONFIG_ prefix to USE_PRIVATE_LIBGCC Masahiro Yamada
2014-02-28 4:37 ` Masahiro Yamada
2014-02-28 4:23 ` [U-Boot] [PATCH v2 3/4] config.mk: specify the exact path to standalone linker script Masahiro Yamada
2014-02-28 4:23 ` [U-Boot] [PATCH v2 4/4] kbuild: improve Kbuild speed Masahiro Yamada
2014-03-02 0:00 ` Simon Glass [this message]
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