Re: [PATCH] ARM: dts: TI: Enable __symbols__ in dtb files for some platforms

[Tom Rini]

On Wed, Aug 16, 2017 at 03:57:21PM -0700, Frank Rowand wrote:
> On 08/16/17 15:33, Frank Rowand wrote:
> > On 08/16/17 14:59, Tom Rini wrote:
> >> Build the dtb file for these platfroms with __symbol__ information
> >> included.  This will reduce the size of the dtb (and resident memory
> > 
> > typo: reduce the size should be increase the size
> > 
> > 
> >> usage) in exchange for allowing more types of overlays to be applied to
> >> the dtb file prior to passing it to Linux and additional functionality
> >> within the kernel when OF_OVERLAY is enabled.
> >>
> >> Cc: Jason Kridner <jkridner@xxxxxxxxxxxxxxx>
> >> Cc: Drew Fustini <drew@xxxxxxxxxxxxxxx>
> >> Cc: Robert Nelson <robertcnelson@xxxxxxxxx>
> >> Cc: Lokesh Vutla <lokeshvutla@xxxxxx>
> >> Cc: Frank Rowand <frowand.list@xxxxxxxxx>
> >> Cc: Rob Herring <robh+dt@xxxxxxxxxx>
> >> Cc: Mark Rutland <mark.rutland@xxxxxxx>
> >> Cc: Russell King <linux@xxxxxxxxxxxxxxx>
> >> Cc: devicetree@xxxxxxxxxxxxxxx
> >> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> >> Cc: linux-kernel@xxxxxxxxxxxxxxx
> >> Signed-off-by: Tom Rini <trini@xxxxxxxxxxxx>
> >> ---
> >> This patch takes the path that Rob encouraged in my previous patch of
> >> enabling __symbols__ in some platforms now (that can use it) and see if
> >> a critical mass evolves that pushes towards -@ being default for all
> >> dtbs.  I would suggest that the dra76 series be respun to include a hunk
> >> like this at least as well, and if there's another Beagle X15 patch,
> >> that too.  Russell, per some of our conversations, something like would
> >> also be needed as part of using overlays to solve some of the problems
> >> with Hummingboard, etc.
> >> ---
> >>  arch/arm/boot/dts/Makefile | 14 ++++++++++++++
> >>  1 file changed, 14 insertions(+)
> >>
> >> diff --git a/arch/arm/boot/dts/Makefile b/arch/arm/boot/dts/Makefile
> >> index 4b17f35dc9a7..6f98422ca00e 100644
> >> --- a/arch/arm/boot/dts/Makefile
> >> +++ b/arch/arm/boot/dts/Makefile
> >> @@ -1063,3 +1063,17 @@ dtb-$(CONFIG_OF_ALL_DTBS) := $(patsubst $(dtstree)/%.dts,%.dtb, $(wildcard $(dts
> >>  
> >>  always		:= $(dtb-y)
> >>  clean-files	:= *.dtb
> >> +
> >> +# enable creation of __symbols__ node
> >> +DTC_FLAGS_am335x-bone += -@
> >> +DTC_FLAGS_am335x-boneblack += -@
> >> +DTC_FLAGS_am335x-boneblack-wireless += -@
> >> +DTC_FLAGS_am335x-boneblue += -@
> >> +DTC_FLAGS_am335x-bonegreen += -@
> >> +DTC_FLAGS_am335x-bonegreen-wireless += -@
> >> +DTC_FLAGS_am57xx-beagle-x15 += -@
> >> +DTC_FLAGS_am57xx-beagle-x15-revb1 += -@
> >> +DTC_FLAGS_dra7-evm += -@
> >> +DTC_FLAGS_dra72-evm += -@
> >> +DTC_FLAGS_dra72-evm-revc += -@
> >> +DTC_FLAGS_dra71-evm += -@
> >>
> > 
> > I would prefer that instead of "-@", a configurable value be used.
> 
> I stated that poorly.  It was intended conceptually, not literally.
> 
> One possible concrete implementation would be to use something other
> than DTC_FLAGS, for example DTC_FLAGS_EXTRA, then have the build
> system choose whether to fold DTC_FLAGS_EXTRA into DTC_FLAGS, based
> on some sort of configurable value.

So you would have to pass in a flag, and then set a CONFIG option for
"please use this flag I just explicitly set" ?

-- 
Tom

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