[U-Boot] [PATCH] README: Clarify use of BSS during SPL board_init_f()
simon.k.r.goldschmidt at gmail.com
Thu Aug 8 18:21:04 UTC 2019
Am 08.08.2019 um 19:54 schrieb Andreas Dannenberg:
> The earlier commit....
> commit a5a5d997b41a ("spl: Allow performing BSS init early before board_init_f()")
> ...introduced the ability to use BSS from SPL's board_init_f() as it may
> be required in certain exceptional use cases so go ahead and update the
> README to reflect this change. Note that as highlighted with the changes
> the use of the associated CONFIG option is generally not recommended.
> Signed-off-by: Andreas Dannenberg <dannenberg at ti.com>
Since I expect the patch adding CONFIG_SPL_EARLY_BSS will stay with us:
Reviewed-by: Simon Goldschmidt <simon.k.r.goldschmidt at gmail.com>
Still, I'd be very happy if someone could come up with an idea of how we
can detect usage of BSS before board_init_r. And patches fixing such
invalid usage would be cool as well.
> Simon, as per separate discussion thread here is a proposal for an
> update to the README. I tried to limit the changes to the what I
> thought was the most relevant section (the details section) of the
> document to strike a balance between documenting it and limiting the
> amount of attention drawn to it...
> Andreas Dannenberg
> Texas Instruments Inc
> README | 7 +++++++
> 1 file changed, 7 insertions(+)
> diff --git a/README b/README
> index b493ffeb2d..be3805689e 100644
> --- a/README
> +++ b/README
> @@ -267,6 +267,13 @@ board_init_f():
> - preloader_console_init() can be called here in extremis
> - should set up SDRAM, and anything needed to make the UART work
> - these is no need to clear BSS, it will be done by crt0.S
> + - for specific scenarios on certain architectures an early BSS *can*
> + be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing
> + of BSS prior to entering board_init_f()) but doing so is discouraged.
> + Instead it is strongly recommended to architect any code changes
> + or additions such to not depend on the availability of BSS during
> + board_init_f() as indicated in other sections of this README to
> + maintain compatibility and consistency across the entire code base.
> - must return normally from this function (don't call board_init_r()
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