[PATCH v2 1/3] cpukit/flash: Add API for Flash devices

[Gedare Bloom]

On Mon, Apr 17, 2023 at 9:55 PM Chris Johns <chrisj at rtems.org> wrote:
>
> On 18/4/2023 1:48 pm, Gedare Bloom wrote:
> > On Sun, Apr 16, 2023 at 6:48 PM Aaron Nyholm
> > <aaron.nyholm at unfoldedeffective.com> wrote:
> >> As for the RTEMS_FLASHDEV_MAX_REGIONS being set at 32 I chose the value as it seamed a good balance between memory usage and function. I wanted to avoid using malloc as your previous feedback suggested. If configurable size is necessary what’s the best way to approach it without using malloc?
> >>
> > A configure-time option may be viable, e.g., spec/build/cpukit/opt*
> > You should probably elevate that question to its own email thread to
> > get other opinions.
>
> Is there an option that shows how to control a defined in an API header?
>
This has mostly been done in the past at a BSP level, so there are
plenty of examples within BSP drivers and frameworks. Whether it is
suitable to a cpukit driver framework is something I don't really
know.

A quick example could be:
BSP_CONSOLE_BAUD
used in bsps/powerpc/shared/console
define in spec/build/bsps/optconsolebaud.yml

I'm not saying this is for sure the right way to do this, but I think
it is worth thinking through.

I think you would have to avoid using the define in the header itself
to make it portable. The way it's defined in this code can be done
with a RTEMS_ZERO_LENGTH_ARRAY. Then the driver that instantiates the
structure can determine for itself the size of how many regions to
support. Even that would be an improvement to the current hard-coded
method. The size itself could be made a field of the rtems_flashdev
that the driver would setup at init time. Whether it is made
configurable in the spec/build approach, or determined by the driver
itself, is less concerning to me than the fact it is currently not
configurable at all and is assumed to be sufficient for all flash
drivers to be 32.

> I have a quick look and could not see anything.
>
> Thanks
> Chris