'of_compatible' and 'model' imd records are unusable

[Sascha Hauer]

On Sat, Oct 02, 2021 at 12:44:47PM +0300, Antony Pavlov wrote:
> On Sat, 2 Oct 2021 10:48:50 +0200
> Sascha Hauer <s.hauer at pengutronix.de> wrote:
> 
> Hi Sascha!
> 
> > On Fri, Oct 01, 2021 at 02:24:53PM +0300, Antony Pavlov wrote:
> > > Hi all!
> > > 
> > > I have cloned barebox c67ada0024da (v2021.08.0) and found that
> > > 'of_compatible' and 'model' imd records are unusable.
> > > 
> > > E.g.
> > > 
> > > barebox$ make ARCH=arm CROSS_COMPILE=aarch64-linux-gnu- imx_v8_defconfig
> > > barebox$ make ARCH=arm CROSS_COMPILE=aarch64-linux-gnu-
> > > ...
> > > images built:
> > > barebox-nxp-imx8mm-evk.img
> > > barebox-prt-prt8mm.img
> > > barebox-nxp-imx8mp-evk.img
> > > barebox-nxp-imx8mq-evk.img
> > > barebox-zii-imx8mq-dev.img
> > > barebox-phytec-phycore-imx8mq.img
> > > 
> > > barebox$ ./scripts/bareboximd images/barebox-nxp-imx8mm-evk.img
> > > build: #1 Fri Oct 1 10:16:30 UTC 2021
> > > buildsystem version: 
> > > crc32: 0x00000000
> > > release: 2021.08.0
> > > barebox$ 
> > > 
> > > There is no 'of_compatible' and 'model' imd records in bareboximd output.
> > > 
> > > So there is no chance to imd_find_type(..., IMD_TYPE_OF_COMPATIBLE)
> > > (see common/bbu.c) in a barebox image file.
> > > 
> > > scripts/gen-dtb-s puts IMD_TYPE_OF_COMPATIBLE and IMD_TYPE_MODEL
> > > records into barebox_imd_0 section.
> > > 
> > > BAREBOX_IMD macro (include/asm-generic/barebox.lds.h)
> > > does not KEEP barebox_imd_0 section":
> > 
> > This is done on purpose because otherwise...
> > 
> > > 
> > > #define BAREBOX_IMD                             \
> > >         STRUCT_ALIGN();                         \
> > >         KEEP(*(.barebox_imd_start))             \
> > >         KEEP(*(.barebox_imd_1*))                \
> > >         *(.barebox_imd_0*)                      \
> > >         KEEP(*(.barebox_imd_end))
> > > 
> > > KEEPing barebox_imd_0 leads to several 'of_compatible' and 'model' records
> > > in one barebox image file, e.g.:
> > 
> > ...exactly this would happen.
> > 
> > To get the of_compatible and model imd tags in an image you have to put
> > IMD_USED_OF() explicitly into the entry function of the image handling
> > this compatible, there's no way for the build process to know which
> > image handles which device tree. See below for an example which adds the
> > tags for the boards you are currently compiling.
> 
> There are two remarks:
> 
> 1. It looks like we still able to automatically add of_compatible and model imd tags.
> Please see my message http://lists.infradead.org/pipermail/barebox/2021-October/037412.html

I gave it a try, it works and looks like a good solution. We'll need
another

if [ "$imd" = "y" ]; then
       echo ".word __imd_${name}_start"
fi

at the end of scripts/gen-dtb-s to make it work with compressed dtbs as
well.

> 
> Can we automaticaly generate of_compatible and model imd tags for most of the boards
> and explicitly generate tags with IMD_USED_OF() just for selected boards?

With your approach we can drop IMD_USED_OF(), at least I see no more
need for it.

Sascha

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