[PATCH rtems-docs] bsps/imxrt: Remove superfluous options from dtc

[Joel Sherrill]

On Mon, May 17, 2021 at 10:06 AM Christian MAUDERER <
christian.mauderer at embedded-brains.de> wrote:

> Hello Joel,
>
> Am 17.05.21 um 14:04 schrieb Joel Sherrill:
> >
> >
> > On Mon, May 17, 2021, 2:35 AM Christian Mauderer
> > <christian.mauderer at embedded-brains.de
> > <mailto:christian.mauderer at embedded-brains.de>> wrote:
> >
> >     The -@ option adds symbols that are used when applying an overlay.
> RTEMS
> >     doesn't support overlays or re-parsing of device trees. So the
> symbols
> >     only increase the size of the binary.
> >
> >     The same is true for the padding. It would be useful if the device
> tree
> >     is changed during run time which is not supported in RTEMS.
> >
> >     Update #4180
> >     ---
> >       user/bsps/arm/imxrt.rst | 2 +-
> >       1 file changed, 1 insertion(+), 1 deletion(-)
> >
> >     diff --git a/user/bsps/arm/imxrt.rst b/user/bsps/arm/imxrt.rst
> >     index 1bce6d7..c60b51d 100644
> >     --- a/user/bsps/arm/imxrt.rst
> >     +++ b/user/bsps/arm/imxrt.rst
> >     @@ -118,7 +118,7 @@ with your FDT source names)::
> >         sh> arm-rtems6-cpp -P -x assembler-with-cpp \
> >                            -I ${PREFIX}/arm-rtems6/imxrt1052/lib/include
> \
> >                            -include "YOUR.dts" /dev/null | \
> >     -            dtc -@ -O dtb -o "YOUR.dtb" -b 0 -p 1024
> >     +            dtc -O dtb -o "YOUR.dtb" -b 0 -p 64
> >         sh> rtems-bin2c -C -N imxrt_dtb "YOUR.dtb" "YOUR.c"
> >
> >       Make sure that your new c file is compiled and linked into the
> >     application.
> >
> >
> > C should be capitalized.
>
> I'll create an extra commit for that because it's an unrelated change.
>
> >
> > Do you think the command should be explained in the docs like you did in
> > the comment?
>
>  From my point of view that is not necessary. I don't see a use case of
> the -@ or a bigger padding in the near or even not so near future.
> Therefore I don't think it's useful to describe options that are _not_
> used for this BSP.
>
>
> I start to think that we sooner or later will have to add some general
> device-tree information to our manual. But I'm not sure yet what and
> where. Basically stuff like:
>
> - What is a device tree. What are the file endings dts and dtb.
> - What is a good source for a device tree (most of the time FreeBSD in
> our case).
>

Vivado or the Xilinux github site for the Xilinx BSPs.


> - How to handle it with U-Boot.
> - How to apply overlays with U-Boot.
> - How to replace it with a device tree that is compiled into the
> application and why it will infect the code with GPL in most cases.
>
> I think we already start to duplicate some of that stuff in the BSP
> documentation. Do you have a suggestion where we could put such a chapter?
>

It seems like a general topic for the BSPs and Device Drivers
manual but you want to make a cross manual reference to it.
And try to cover a lot in there from a general sense so the BSP
specific sections can say "we use U-Boot with this one detail
specific to this board"

Maybe viewing it from a consumer and producer viewpoint is
helpful. The BSP tends to consume it and that process needs
to go in the BSP guide. But some details may be BSP specific
and that needs to be in the BSP specific area. Try to cover as
much in the general BSP guide as possible.


> Best regards
>
> Christian
>
> >
> >     --
> >     2.26.2
> >
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> >
>
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