Re: [PATCH 1/2] imd: create new helper macro to add data from oftree to image meta data

[Sascha Hauer <s.hauer@pengutronix.de>]

On Fri, Feb 22, 2019 at 10:22:34PM +0100, Uwe Kleine-König wrote:
> On Fri, Feb 22, 2019 at 09:11:39AM +0100, Sascha Hauer wrote:
> > Hi Uwe,
> > 
> > On Thu, Feb 21, 2019 at 11:25:30AM +0100, Uwe Kleine-König wrote:
> > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> > > ---
> > >  include/image-metadata.h | 4 ++++
> > >  scripts/gen-dtb-s        | 4 ++--
> > >  2 files changed, 6 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/include/image-metadata.h b/include/image-metadata.h
> > > index 8739bffb92e1..5904d95acd37 100644
> > > --- a/include/image-metadata.h
> > > +++ b/include/image-metadata.h
> > > @@ -118,6 +118,10 @@ static inline void imd_used(const void *unused)
> > >  
> > >  #define IMD_USED(_name) \
> > >  	imd_used(&__barebox_imd_##_name)
> > > +#define IMD_USED_OF(_name) ({ \
> > > +	extern char __barebox_imd_OF_ ## _name[]; \
> > > +	imd_used(&__barebox_imd_OF_ ## _name); \
> > > +	})
> > >  
> > >  #endif /* __BAREBOX__ */
> > >  
> > > diff --git a/scripts/gen-dtb-s b/scripts/gen-dtb-s
> > > index 2b44ffb361eb..c3144df851bf 100755
> > > --- a/scripts/gen-dtb-s
> > > +++ b/scripts/gen-dtb-s
> > > @@ -18,8 +18,8 @@ FDTGET=scripts/dtc/fdtget
> > >  
> > >  if [ "$imd" = "y" ]; then
> > >  	echo ".section .barebox_imd_0.${name},\"a\""
> > > -	echo ".global __imd_${name}_start"
> > > -	echo "__imd_${name}_start:"
> > > +	echo ".global __barebox_imd_OF_${name}"
> > > +	echo "__barebox_imd_OF_${name}:"
> > 
> > This breaks somewhere when the compressed variants of the dtbs are used.
> > Building imx_v7_defconfig fails here with:
> > 
> > arch/arm/dts/built-in-pbl.o: In function `__dtb_z_imx6dl_wandboard_end':
> > arch/arm/dts/pbl-vf610-zii-ssmb-spu3.dtb.o:(.dtbz.rodata.imx6dl_wandboard+0x2340): undefined reference to `__imd_imx6dl_wandboard_start'
> >   OBJCOPYB images/start_imx6dl_nitrogen6x_1g.pblb
> > arch/arm/dts/built-in-pbl.o: In function `__dtb_z_imx6q_wandboard_end':
> > arch/arm/dts/pbl-vf610-zii-ssmb-spu3.dtb.o:(.dtbz.rodata.imx6q_wandboard+0x2320): undefined reference to `__imd_imx6q_wandboard_start'
> 
> The following makes it build again (on top of my patch):
> 
> diff --git a/scripts/gen-dtb-s b/scripts/gen-dtb-s
> index c3144df851bf..90294c4840f4 100755
> --- a/scripts/gen-dtb-s
> +++ b/scripts/gen-dtb-s
> @@ -71,5 +71,5 @@ echo ".global __dtb_z_${name}_end"
>  echo ".balign STRUCT_ALIGNMENT"
>  
>  if [ "$imd" = "y" ]; then
> -       echo ".word __imd_${name}_start"
> +       echo ".word __barebox_imd_OF_${name}"
>  fi
> 
> But I admit I don't understand why this is referenced here. Also I
> wonder why imx_defconfig + CONFIG_MACH_PHYTEC_SOM_IMX6=y doesn't fail.

We are using -fdata-sections -ffunction-sections to throw away unused
data and functions. In gen-dtb-s the lines you are changing in your
fixups do not have a separate section, so it ends up in the section that
has previously been set which here is: .section .dtbz.rodata.${name},\"a\"
So when the wandboard pulls in the symbol __dtb_z_imx6q_wandboard_start
then we must also have __imd_imx6q_wandboard_start.

I wonder which purpose these lines have anyway. Nothing in the code
seems to reference __imd_*_start, so I just removed the lines for now.

Sascha

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