Hi Simon,
2015-02-21 4:20 GMT+09:00 Simon Glass <s...@chromium.org>: > Hi Stephen, > > On 19 February 2015 at 14:13, Stephen Warren <swar...@wwwdotorg.org> wrote: >> On 02/19/2015 12:55 AM, Masahiro Yamada wrote: >>> >>> When Kconfig for U-boot was examined, one of the biggest issues was >>> how to support multiple images (Normal, SPL, TPL). There were >>> actually two options, "single .config" and "multiple .config". >>> After some discussions and thought experiments, I chose the latter, >>> i.e. to create ".config", "spl/.config", "tpl/.config" for Normal, >>> SPL, TPL, respectively. >>> >>> It is true that the "multiple .config" strategy provided us the >>> maximum flexibility and helped to avoid duplicating CONFIGs among >>> Normal, SPL, TPL, but I have noticed some fatal problems: >>> >>> [1] It is impossible to share CONFIG options across the images. >>> If you change the configuration of Main image, you often have to >>> adjust some SPL configurations correspondingly. Currently, we >>> cannot handle the dependencies between them. It means one of the >>> biggest advantages of Kconfig is lost. >>> >>> [2] It is too painful to change both ".config" and "spl/.config". >>> Sunxi guys started to work around this problem by creating a new >>> configuration target. Commit cbdd9a9737cc (sunxi: kconfig: Add >>> %_felconfig rule to enable FEL build of sunxi platforms.) added >>> "make *_felconfig" to enable CONFIG_SPL_FEL on both images. >>> Changing the configuration of multiple images in one command is a >>> generic demand. The current implementation cannot propose any >>> good solution about this. >>> >>> [3] Kconfig files are getting ugly and difficult to understand. >>> Commit b724bd7d6349 (dm: Kconfig: Move CONFIG_SYS_MALLOC_F_LEN to >>> Kconfig) has sprinkled "if !SPL_BUILD" over the Kconfig files. >>> >>> [4] The build system got more complicated than it should be. >>> To adjust Linux-originated Kconfig to U-Boot, the helper script >>> "scripts/multiconfig.sh" was introduced. Writing a complicated >>> text processor is a shell script sometimes caused problems. >>> >>> Now I believe the "single .config" will serve us better. With it, >>> all the problems above would go away. Instead, we will have to add >>> some CONFIG_SPL_* (and CONFIG_TPL_*) options such as CONFIG_SPL_DM, >>> but we will not have much. Anyway, this is what we do now in >>> scripts/Makefile.spl. >>> >>> I admit my mistake with my apology and this commit switches to the >>> single .config configuration. >>> >>> It is not so difficult to do that: >>> >>> - Remove unnecessary processings from scripts/multiconfig.sh >>> This file will remain for a while to support the current defconfig >>> format. It will be removed after more cleanups are done. >>> >>> - Adjust some makefiles and Kconfigs >>> >>> - Add some entries to include/config_uncmd_spl.h and the new file >>> scripts/Makefile.uncmd_spl. Some CONFIG options that are not >>> supported on SPL must be disabled because one .config is shared >>> between SPL and U-Boot proper going forward. I know this is not >>> a beautiful solution and I think we can do better, but let's see >>> how much we will have to describe them. >>> >>> - update doc/README.kconfig >>> >>> More cleaning up patches will follow this. >> >> >>> diff --git a/arch/arm/cpu/armv7/tegra-common/Kconfig >>> b/arch/arm/cpu/armv7/tegra-common/Kconfig >>> index 0de13ae..c9e8919 100644 >>> --- a/arch/arm/cpu/armv7/tegra-common/Kconfig >>> +++ b/arch/arm/cpu/armv7/tegra-common/Kconfig >>> @@ -26,7 +26,7 @@ config SYS_MALLOC_F_LEN >>> default 0x1800 if SYS_MALLOC_F >>> >>> config USE_PRIVATE_LIBGCC >>> - default y if SPL_BUILD >>> + default y >>> >>> config DM >>> default y if !SPL_BUILD >> >> >> I think the above patch demonstrates the problem very nicely; it changes the >> semantics from having CONFIG_USE_PRIVATE_LIBGCC enabled only in SPL build to >> having it enabled everywhere. While that particular change shouldn't be an >> issue, I think that requiring that all config options to have the same value >> in main/SPL/TPL will be. For example, how do we disabled MMC support in SPL? >> We have to introduce separate CONFIG_MMC and CONFIG_SPL_MMC don't we? That >> doesn't seem any better than having separate defconfig files for >> SPL/non-SPL, or using ifdefs in a single defconfig file. What happened to >> the ability of one defconfig file to include another, so options could be >> shared between the two? > > We use separate options for normal and SPL now. Currently we have > CONFIG_SPL_MMC_SUPPORT. So it already works this way. > > If we can move to a world where SPL and U-Boot are more similar that > will be good. > > What I don't understand about this change is why we cannot have > 'default y if SPL_BUILD' in a rule if we want to. It seems like that > would be useful. CONFIG_SPL_BUILD is not defined in Kconfig any more, i.e. we can not use the "if SPL_BUILD" conditonal. It is given when descending into the spl directory, like the pre-kconfig build. Here in scripts/Makefile.spl -include include/config/auto.conf -include $(obj)/include/autoconf.mk KBUILD_CPPFLAGS += -DCONFIG_SPL_BUILD ifeq ($(CONFIG_TPL_BUILD),y) KBUILD_CPPFLAGS += -DCONFIG_TPL_BUILD endif -- Best Regards Masahiro Yamada _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
