[U-Boot] [PATCH 1/2] common: mark commands as default to match "config_cmd_default.h"

[Simon Glass]

Hi Masahiro,

On 15 January 2015 at 12:10, Masahiro YAMADA <yamada.m at jp.panasonic.com> wrote:
> Hi
>
> 2015-01-15 23:46 GMT+09:00 Simon Glass <sjg at chromium.org>:
>> Hi,
>>
>> On 14 January 2015 at 01:18, Alexey Brodkin <Alexey.Brodkin at synopsys.com> wrote:
>>> Hi Simon, Masahiro-san,
>>>
>>> On Tue, 2015-01-13 at 20:18 -0800, Simon Glass wrote:
>>>> >
>>>> >> Probably I'm missing details of our Kconfig migration plan if one
>>>> >> exists. Then I'd like to get a reference to the plan so I'm not
>>>> >> attempting to do things that are already scheduled and could be even in
>>>> >> a process of implementation.
>>>> >> Otherwise if there's no current plan for Kconfig migration we may start
>>>> >> discussion on how to deal with "commands" in particular.
>>>> >
>>>> >
>>>> > I proposed the following way, but no big conversion movement has happened yet.
>>>> > http://thread.gmane.org/gmane.comp.boot-loaders.u-boot/199965/focus=200089
>>>> >
>>>> > If you have an idea, please propose it.
>>>
>>> Unfortunately I cannot open this link - I see "Connection to 80.91.229.5
>>> failed". Do you mind to provide a link for the same message in
>>> http://lists.denx.de ?
>>>
>>>
>>>> > Kconfig conversion is a too big task to be done by a single indivisual.
>>>> > Any suggestion, any form of contribution is very appreciated.
>>>
>>> Indeed and that stops me from starting this work as well.
>>> So my point is:
>>>  1) anybody may do updates to Kconfig like add more U-Boot commands,
>>> some settings (CONFIG_SYS_xxx)
>>>  2) board maintainers are responsible for updates in defconfigs and
>>> corresponding headers in "include/configs/"
>>>  3) that would be helpful if at (1) board maintainers are notified via
>>> direct emails on the change that has been done
>>>
>>>> > I personally keep away from any global changes until
>>>> > non-generic boards are dumped.
>>>> >
>>>> > As Tom said in the following mail,
>>>> > http://lists.denx.de/pipermail/u-boot/2015-January/201032.html
>>>> > we are going to remove lots of boards.
>>>> >
>>>> > I do not want to make extra efforts on non-generic boards.
>>>
>>> That makes sense but why don't we start implementation of changes in
>>> good boards we know already converted to "generic"? There're even entire
>>> arches that switched to "generic boards".
>>>
>>>> >> The point is commands are low-hanging fruits in terms of Kconfig
>>>> >> migration - there're no extra options and tweaks, once all commands are
>>>> >> added in Kconfig (essentially with dependencies etc) we may clean all
>>>> >> board headers. The only real problem here is amount of work - lots of
>>>> >> headers/defconfigs to patch. But still this is doable.
>>>> >
>>>> >
>>>> > I realized one problem when I was doing this task
>>>> > for my boards in commit 25e274e20208.
>>>> >
>>>> > The defconfigs of my boards are almost the same:
>>>> > (configs/ph1_ld4_defconfig, configs/ph1_pro4_defconfig, configs/ph1_sld8_defconfig)
>>>> >
>>>> > What is inconvenient as for defconfig is that
>>>> > it does not support "include" directive like C headers.
>>>> >
>>>> > People generally like to add CONFIG_CMD_* to a common header file
>>>> > such as include/configs/tegra-common.h
>>>> >
>>>> > On the other hand, on defconfig, we must touch each defconfig of the board family.
>>>> >
>>>> > I have not been able to decide right direction to solve this issue.
>>>> >
>>>> > I think we need to discuss about how to live with lots of defconfigs.
>>>>
>>>> How about this:
>>>>
>>>> 1. Support an 'include' option in defconfig to include another file.
>>>> This could take the form of CONFIG_DEFCONFIG_INCLUDES (comma-separated
>>>> list of filenames). Don't allow nested includes - this CONFIG provides
>>>> a complete list of includes.
>>>> 2. When you use menuconfig to edit the config, it ignores the include
>>>> and just writes out everything. Then it runs a simple script which
>>>> parses the include files, and adjusts the file so that things in the
>>>> includes are not repeated in the defconfig.
>>>>
>>>> I think this scheme would be good enough, but can probably be
>>>> improved. At least it would be better than what we have.
>>>>
>>>> Or we could instead define particular includes for different purposes:
>>>>
>>>> - Arch
>>>> - SOC
>>>> - SOC Vendor
>>>> - Board vendor
>>>> - Board family
>>>>
>>>> We could then require that standard filenames are used, and search for
>>>> the correct file based on the SOC/board/vendor setting, etc.
>>>>
>>>> As an example, for trimslice, we could search for arm.h, tegra.h,
>>>> nvidia.h, compulab.h, some_family_name.h.
>>>>
>>>> This is less flexible though.
>>>
>>> Frankly I don't like this approach with post-processing steps. It will
>>> inevitably end-up with messed up configs.
>>>
>>> Why don't we just use default values in Kconfig for ARCH/SOC/Board?
>>> It's pretty obvious that 1 board may have N flavors but then have a
>>> baseline options selected in "board/vendor/board_name/Kconfig" and only
>>> put options that differ between boards in your defconfigs.
>>>
>>> This way "savedefconfig" will automatically strip down all extra lines
>>> for a particular board.
>>>
>>> This is how things work in Linux kernel and Buildroot Kconfig-based
>>> build systems. Probably I'm missing something here because U-Boot
>>> differs from mentioned projects in some aspects - if so please correct
>>> me.
>>
>> I started with this approach and Masahiro was not very keen on it. I'm
>> OK with it, particularly as it is already supported, but I wonder
>> whether we can do better.
>
> Honestly, I do not like baseline options in board-Kconfig very much.
> The advantage is that it works without any change.
>
>
> What I suggested before was to use scripts/kconfig/merge_config.sh.
>
> For example, put the SoC baseline options into tegra30_defconfig.
> Put the difference from that into tegra30_(board).config
> For example,
>
>     make  tegra30_defconfig  tegra30_seaboard.config
>     make  tegra30_defconfig  tegra30_trimslice.config
>
> The disadvantage is that we would have to input more for the configuration
> and has some impact on other projects such as BuildRoot...

Is there any way that tegra30_seaboard could include tegra30 automatically?

>
>
>
> Another option is "multi-image".
> Actually barebox adopted this solution to solve the increasing
> defconfig problem.
>
> In barebox, for example, all the Tegra boards share a single
> defconfig, "tegra_v7_defconfig"
>
> tegra_v7_defconfig  creates images for beaver, jetson, colibri, ac100, ...
>
> It takes advantage of Device Tree configuration and garbage collection.
> So, it generates multipule images without increasing memory foot-print.
>

I've been keen on that approach and have taken some steps for Tegra
and Exynos. Exynos is actually not to far away, but Tegra 124 pinmux
approach makes this hard.

Still I think this is the best solution - fewer boards to build also.

>
>
>
>> I notice that some kernel distributions have a script which pulls out
>> common kernel configs in a separate file (e.g. for ARM, or for Tegra)
>> for checking into source control, then combine them again for the
>> kernel. This suggests that others have this problem too. It does seem
>> like a convenient feature to be able to have some sort of hierarchy of
>> config.
>>
>> Re messed-up configs, what will mess up? We can make it part of
>> writing the config, perhaps.
>
> The hierarchical config strategy makes "savedefconfig" difficult , I think.
>

I never said it would be easy. Kconfig wasn't easy.

>
>
>>>
>>>> >>
>>>> >> That's a separate topic. I do agree that CMD_FPGA makes not much sense
>>>> >> for most of boards, as well as some others.
>>>> >>
>>>> >> And I think during migration process of commands to Kconfig it's a good
>>>> >> time to reconsider default commands.
>>>> >
>>>> > Agree.
>>>> > We should reconsider the default.
>>>> > In my opition, most of the ones in config_cmd_default.h are not default commands.
>>>
>>> Right but if we expect to switch to Kconfig solely for commands
>>> selection we may not care much about contents of "config_cmd_default.h"
>>> assuming it will go away sometime soon.
>>>
>>> Probably we may just focus on:
>>> 1. Add all existing commands in Kconfig
>>> 2. Select very few of them to be globally default
>>>
>>> (1) is pretty simple and anybody may do it if time permits
>>> (2) requires wide discussion
>>>
>>> But what's really nice with Kconfig is its "savedefconfig". So we may
>>> not set any commands as globally default and let every architecture,
>>> board or defconfig to select really required options.
>>>
>>> Then once any option is marked as global (or even arch or board) default
>>> in a matter of simple script that does "make XXX_defconfig && make
>>> savedefconfig && mv defconfig configs/XXX_defconfig" all relevant
>>> defconfigs will be correctly updated (default options will be stripped
>>> out).
>>
>> Yes, it would be great to get all command configs into Kconfig.
>>
>> I wonder if we need a script which automates the conversion? The
>> header file includes in the include/configs/... files makes this
>> non-trivial. But if we had a script which could take a CONFIG as a
>> parameter, remove it from all config headers, and add it to relevant
>> defconfigs, it would be very useful.
>
> I have a Python script that moves each CONFIG from header files to
> defconfig files.
>
> I wrote it for my local use, so it might not be very clean.
>
>
> If necessary, I can share it on ML.

Yes please!

- Simon