This introduces the variabe DTC_EXTRA_FLAGS to allow for additional flags to be passed to dtc. While this can have many uses (such as easier testing of new warning flags) the use case I wish to spell out here is passing of -@ to enable __symbols__ to be included in the resulting dtb and thus 'stacked' overlays to be able to be used. When passing in -@ this will increase the size of the dtb (and resident memory 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 and in tools outside of the kernel. 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: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> Cc: Michal Marek <mmarek@xxxxxxxx> CC: linux-kbuild@xxxxxxxxxxxxxxx Cc: devicetree@xxxxxxxxxxxxxxx Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Signed-off-by: Tom Rini <trini@xxxxxxxxxxxx> --- This would be v3 of my attempt to enable __symbols__ more widely (v2, for people not on the CC, enabled it always, but for some boards). To be clear, this version of the patch is more flexible in that it allows for arbitrary flags to be passed to dtc, which can have other uses. But, I'm still spelling out -@ being the motivation behind this for clarity. Both Frank and Rob were uncomfortable with v2, and Frank suggested this approach to make it easier for users / distributions / etc to opt-in to this functionality. For clarity, Frank was suggesting (at least at first) perhaps also a tie-in CONFIG option, which I have not done here as I feel that's adding extra hurdles to something that must already be opt-in. Given that today many of the immediate uses are for "pre-boot" application of overlays (SoM + carrier + add-ons or EVM + LCD for example), I believe this is an acceptable trade-off to make currently. --- scripts/Makefile.lib | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index 58c05e5d9870..04434ffe3370 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -293,7 +293,7 @@ DTC_FLAGS += -Wnode_name_chars_strict \ -Wproperty_name_chars_strict endif -DTC_FLAGS += $(DTC_FLAGS_$(basetarget)) +DTC_FLAGS += $(DTC_FLAGS_$(basetarget)) $(DTC_EXTRA_FLAGS) # Generate an assembly file to wrap the output of the device tree compiler quiet_cmd_dt_S_dtb= DTB $@ -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
