On Sat, Feb 25, 2023 at 11:38 AM Simon Glass <s...@chromium.org> wrote: > > +Masahiro Yamada
I do not know. This seems a shorthand in Kconfig level. masahiro@zoe:~/ref/u-boot(master)$ rgrep '^config SPL_' | wc 540 1080 24872 masahiro@zoe:~/ref/u-boot(master)$ rgrep '^config TPL_' | wc 163 326 7462 If hundreds of duplications are not manageable, go for it, but kconfig will be out-of-sync from the upstream Kconfig. Masahiro > On Fri, 24 Feb 2023 at 19:04, Simon Glass <s...@chromium.org> wrote: >> >> +lk >> >> On Sun, 19 Feb 2023 at 14:55, Simon Glass <s...@chromium.org> wrote: >> > >> > In the case of Linux, only one build is produced so there is only a >> > single configuration. For other projects, such as U-Boot and Zephyr, the >> > same code is used to produce multiple builds, each with related (but >> > different) options enabled. >> > >> > This can be handled with the existing kconfig language, but it is quite >> > verbose, somewhat tedious and very error-prone, since there is a lot of >> > duplication. The result is hard to maintain. >> > >> > Describe an extension to the Kconfig language to support easier handling >> > of this use case. >> > >> > Signed-off-by: Simon Glass <s...@chromium.org> >> > --- >> > >> > Documentation/kbuild/kconfig-language.rst | 134 ++++++++++++++++++++++ >> > 1 file changed, 134 insertions(+) >> > >> > diff --git a/Documentation/kbuild/kconfig-language.rst >> > b/Documentation/kbuild/kconfig-language.rst >> > index 858ed5d80defe..73fb016a5533f 100644 >> > --- a/Documentation/kbuild/kconfig-language.rst >> > +++ b/Documentation/kbuild/kconfig-language.rst >> > @@ -228,6 +228,24 @@ applicable everywhere (see syntax). >> > enables the third modular state for all config symbols. >> > At most one symbol may have the "modules" option set. >> > >> > +- phase declaration: "defphase" >> > + This defines a new build phase. See `Build Phases`_. >> > + >> > +- default phase: "phasedefault" >> > + This indicates the default build phase. See `Build Phases`_. >> > + >> > +- add entries for phases: "addphases" >> > + This creates new phase-specific entries based on a template entry and >> > adds >> > + the same attributes to it. See `Build Phases`_. >> > + >> > +- set entries for phases: "setphases" >> > + This sets the phases which need an entry. This allows creating an entry >> > that >> > + only has a primary phase. See `Build Phases`_. >> > + >> > +- indicate a phase-specific attribute: "forphases" >> > + This marks an attribute as being applicable only to a particular phase >> > or >> > + group of phases. See `Build Phases`_. >> > + >> > Menu dependencies >> > ----------------- >> > >> > @@ -319,6 +337,119 @@ MODVERSIONS directly depends on MODULES, this means >> > it's only visible if >> > MODULES is different from 'n'. The comment on the other hand is only >> > visible when MODULES is set to 'n'. >> > >> > +Build Phases >> > +------------ >> > + >> > +Some projects use Kconfig to control multiple build phases, each phase >> > +resulting in a separate set of object files and executable. This is the >> > +case in U-Boot [12]_. Zephyr OS seems to be heading this way too [13]_. >> > + >> > +Generally the phases are related, so that enabling an entry in the primary >> > +phase also enables it by default in the others. But in some cases it may >> > +be desirable to use separate conditions for each phase. >> > + >> > +All phases have a phase name, for example `SPL`. This name is used as a >> > +prefix to each entry used in that phase, with an underscore in between. >> > +So if FOO is the primary entry, the equivalent entry for the SPL phase >> > +is SPL_FOO. The primary phase is marked with a "phasedefault" entry. >> > + >> > +Phases are declared like any other menu entry except that also have a >> > +"defphase" keyword. Phase entries are normally hidden so do not have a >> > +prompt:: >> > + >> > + config PPL >> > + bool >> > + defphase "Primary Program Loader" >> > + phasedefault >> > + help >> > + This is the primary bootloader. >> > + >> > + config SPL >> > + bool >> > + defphase "Secondary Program Loader" >> > + help >> > + This is used to set up memory and load the primary bootloader. >> > + >> > +The default phase (here PPL) is assumed for all entries, in the sense that >> > +all entries are present in PPL by default and no prefix is needed on these >> > +entries. So FOO means that it applies to PPL. There must be exactly one >> > +default phase. >> > + >> > +The resulting menu entries can be used normally throughout the Kconfig. >> > With >> > +this technique, the different build phases can be fully and individually >> > +controlled from Kconfig. >> > + >> > +However it is not ideal. Often the secondary phases have far fewer >> > entries than >> > +the primary phase, since they offer fewer features. Even so, each FOO >> > that is >> > +needed in a phase must have an SPL_FOO, etc. To avoid an explosion of >> > entries, >> > +it is possible to indicate which are enabled, as a shortcut for creating >> > new >> > +entries:: >> > + >> > + config FOO >> > + bool "Enable foo feature" >> > + addphases SPL >> > + depends on %BAR >> > + depends on QUX >> > + forphases SPL depends on FIZZ >> > + >> > +Note that "%" expands to the phase, so this is equivalent to (ignoring >> > BAR):: >> > + >> > + config FOO >> > + bool "Enable foo feature" >> > + depends on BAR >> > + depends on QUX >> > + >> > + config SPL_FOO # Phase is prepended >> > + bool "Enable foo feature (SPL)" # Suffix is added >> > + depends on SPL_BAR # "%" dependency is expanded >> > + depends on QUX >> > + depends on FIZZ # Added only for SPL >> > + depends on SPL # Added automatically >> > + >> > +Attributes declared in the primary symbol FOO (such as "depends on BAR") >> > also >> > +apply to the secondary ones. >> > + >> > +An entry without any 'addphases' attribute applies to all phases. >> > Individual >> > +phase entries are not available in that case. If the entry is enabled, >> > then >> > +it is enabled for all phases. Only one entry appears in the resulting >> > Kconfig. >> > + >> > +In the case where an entry should apply only to the primary phase (or a >> > +particular set of phases), you can uses "setphases" instead of >> > "addphases":: >> > + >> > + config FOO >> > + bool "Enable foo feature" >> > + setphases PPL >> > + >> > +This means that even if the option is enabled, it will not be active >> > outside >> > +the primary-phase build, here named "PPL". >> > + >> > +Internally, phases are implemented simply by creating new entries. These >> > +appear in the Kconfig as per normal. It would be possible for a Kconfig >> > +editor to show the entries just for a particular phase, leaving out the >> > +entries not applicable to that phase. >> > + >> > +When phases are used, the Kconfig tool outputs separate auto.conf files >> > for >> > +each phase (e.g. auto_spl.conf), so that if SPL_FOO is enabled, then >> > +`CONFIG_FOO=y` is present in the file. This makes it easy for the build >> > system >> > +to build the correct code, use IS_ENABLED(), etc. >> > + >> > +To ensure that the correct options are enabled for each build, in >> > addition to >> > +the normal CONFIG_FOO option in the file, phase symbols are added too. For >> > +example, if FOO is enabled in the SPL phase, then auto_spl.conf contains:: >> > + >> > + CONFIG_FOO=y >> > + CONFIG_SPL_FOO=y >> > + >> > +The phase-specific line (CONFIG_SPL_FOO) is seldom needed, but it allows >> > one >> > +phase to access the symbols from another phase. For example, if the >> > primary >> > +phase needs to receive boot timings from SPL, then support for boot >> > timings must >> > +be added in both phases. If the timings are at a fixed address, this can >> > be in a >> > +shared symbol (like CONFIG_SPL_TIMING_BASE) that both phases can access. >> > + >> > +Technical note: the grammar definition of <symbol> in this documeent does >> > not >> > +include the "%" prefix at present. It can be used with any attribute. It >> > cannot >> > +be used with any top-level items, like "config", "menuconfig", "if" and >> > "menu". >> > + >> > >> > Kconfig syntax >> > -------------- >> > @@ -744,3 +875,6 @@ https://kernelnewbies.org/KernelProjects/kconfig-sat >> > .. [9] https://www4.cs.fau.de/Publications/2011/tartler_11_eurosys.pdf >> > .. [10] https://paulgazzillo.com/papers/esecfse21.pdf >> > .. [11] https://github.com/paulgazz/kmax >> > + >> > +.. [12] https://u-boot.readthedocs.io/en/latest/develop/spl.html >> > +.. [13] https://docs.zephyrproject.org/latest/build/sysbuild/index.html >> > -- >> > 2.39.2.637.g21b0678d19-goog >> > -- Best Regards Masahiro Yamada