[PATCH v12 00/24] Modernize U-Boot shell

[Tom Rini]

On Fri, Dec 08, 2023 at 11:30:01PM +0100, Francis Laniel wrote:

> Hi.
> 
> 
> During 2021 summer, Sean Anderson wrote a contribution to add a new shell, based
> on LIL, to U-Boot [1, 2].
> While one of the goals of this contribution was to address the fact actual
> U-Boot shell, which is based on Busybox hush, is old there was a discussion
> about adding a new shell versus updating the actual one [3, 4].
> 
> So, in this series, with Harald Seiler, we updated the actual U-Boot shell to
> reflect what is currently in Busybox source code.
> Basically, this contribution is about taking a snapshot of Busybox shell/hush.c
> file (as it exists in commit 37460f5da) and adapt it to suit U-Boot needs.
> 
> This contribution was written to be as backward-compatible as possible to avoid
> breaking the existing.
> So, the modern hush flavor offers the same as the actual, that is to say:
> 1. Variable expansion.
> 2. Instruction lists (;, && and ||).
> 3. If, then and else.
> 4. Loops (for, while and until).
> No new features offered by Busybox hush were implemented (e.g. functions).
> 
> It is possible to change the parser at runtime using the "cli" command:
> => cli print
> old
> => cli set modern
> => cli print
> modern
> => cli set old
> The default parser is the old one.
> Note that to use both parser, you would need to set both
> CONFIG_HUSH_MODERN_PARSER and CONFIG_HUSH_OLD_PARSER.
> 
> In terms of testing, new unit tests were added to ut to ensure the new behavior
> is the same as the old one and it does not add regression.
> Nonetheless, if old behavior was buggy and fixed upstream, the fix is then added
> to U-Boot [5].
> In sandbox, all of these tests pass smoothly:
> => printenv board
> board=sandbox
> => ut hush
> Running 20 hush tests
> ...
> Failures: 0
> => cli set modern
> => ut hush
> Running 20 hush tests
> ...
> Failures: 0
> 
> Thanks to the effort of Harald Seiler, I was successful booting a board:
> => printenv fdtfile
> fdtfile=amlogic/meson-gxl-s905x-libretech-cc.dtb
> => cli get
> old
> => boot
> ...
> root at lepotato:~#
> root at lepotato:~# reboot
> ...
> => cli set modern
> => cli get
> modern
> => printenv fdtfile
> fdtfile=amlogic/meson-gxl-s905x-libretech-cc.dtb
> => boot
> ...
> root at lepotato:~#
> 
> This contribution indeed adds a lot of code and there were concern about its
> size [6, 7].
> With regard to the amount of code added, the cli_hush_upstream.c is 13030 lines
> long but it seems a smaller subset is really used:
> gcc -D__U_BOOT__ -E common/cli_hush_upstream.c | wc -l
> 2870
> Despite this, it is better to still have the whole upstream code for the sake of
> easing maintenance.
> With regard to memory size, I conducted some experiments for version 8 of this
> series and for a subset of arm64 boards and found the worst case to be 4K [8].
> Tom Rini conducted more research on this and also found the increase to be
> acceptable [9].
> 
> If you want to review it - your review will really be appreciated - here are
> some information regarding the commits:
> * commits marked as "test:" deal with unit tests.
> * commit "cli: Add Busybox upstream hush.c file." copies Busybox shell/hush.c
> into U-Boot tree, this explain why this commit contains around 12000 additions.
> * commit "cli: Port Busybox 2021 hush to U-Boot." modifies previously added file
> to permit us to use this as new shell.
> The really good idea of #include'ing Busybox code into a wrapper file to define
> some particular functions while minimizing modifications to upstream code comes
> from Harald Seiler.
> * commit "cmd: Add new parser command" adds a new command which permits
> selecting parser at runtime.
> I am not really satisfied with the fact it calls cli_init() and cli_loop() each
> time the parser is set, so your reviews would be welcomed.
> * Other commits focus on enabling features we need (e.g. if).
> 
> Changes since:
>  v2:
>   * Added a small fix to compile sandbox with NO_SDL=1.
>   * Added a command to change parser at runtime.
>   * Added 2021 parser function to all run_command*().
>  v3:
>   * Various bug fixes pointed by the CI.
>   * Added upstream busybox hush commits until 6th February 2022.
>  v4:
>   * Various cleaning.
>   * Modified python test to accept failure output when the test are designed to
>   fail.
>   * Bumped upstream busybox hush commits until 24h March 2022.
>  v5:
>   * Bumped upstream busybox hush commits until 30th January 2023.
>   * Fix how hush interprets '<' and '>', indeed we needed to escape them but I
>   removed this behavior as tests are handled by test command and not hush
>   itself. This permitted to have the ut fdt to pass.
>   * Fix a problem with how exit was handled. This was reported by the ut exit
>   test.
>  v6:
>   * There was no v6 and I got mixed up with version.
>  v7:
>   * Bumped upstream busybox hush commits until 9th May 2023.
>   * Renamed parser command to change parser at runtime to cli and added
>   documentation.
>   * Added better separation of patches.
>   * Removed code about __gnu_thumb1_case_si as it was merged in another series.
>   * Various cleaning.
>  v8:
>   * Bumped upstream busybox hush commits until 25th May 2023.
>  v9:
>   * Bumped upstream busybox hush commits until 2nd October 2023.
>  v10:
>   * Fixed a build error in commit adding cli command.
>   * Add new CONFIG_HUSH_SELECTABLE to only build cli command if the two shell
>   flavors are selected.
>  v11:
>   * Renamed everything containing 2021 to modern.
>   * Fixed cmd Kconfig indentation.
>   * Set modern parser as default for majority of boards except some.

Thanks, this looks good overall and I'll put things in CI soon and aim
to get this in to -next and v2024.04.

-- 
Tom
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