+frank On 1/26/21 1:20 AM, Uwe Kleine-König wrote: > Hello Masahiro, > > On 1/25/21 10:53 PM, Masahiro Yamada wrote: >> On Mon, Jan 25, 2021 at 8:07 PM Uwe Kleine-König <uwe@xxxxxxxxxxxxxxxxx> wrote: >>> >>> Adding the -@ switch to dtc results in the binary devicetrees containing >>> a list of symbolic references and their paths. This is necessary to >>> apply device tree overlays e.g. on Raspberry Pi as described on >>> https://www.raspberrypi.org/documentation/configuration/device-tree.md. >>> >>> Obviously the downside of this change is an increas of the size of the >>> generated dtbs, for an arm out-of-tree build (multi_v7_defconfig): >>> >>> $ du -s arch/arm/boot/dts* >>> 101380 arch/arm/boot/dts-pre >>> 114308 arch/arm/boot/dts-post >>> >>> so this is in average an increase of 12.8% in size. >>> >>> Signed-off-by: Uwe Kleine-König <uwe@xxxxxxxxxxxxxxxxx> >> >> >> (CCing DT ML.) > > makes sense, thanks. > >> https://www.spinics.net/lists/linux-kbuild/msg27904.html >> >> See Rob's comment: >> >> "We've already rejected doing that. Turning on '-@' can grow the dtb >> size by a significant amount which could be problematic for some >> boards." > > The patch was created after some conversation on irc which continued > after I sent the patch. I added the participating parties to Cc:. > > The (relevant) followups were: > > Geert suggested to always generate the symbols and provide a way to > strip the symbols for installation if and when they are not needed. > > Rob said: "I'm less concerned with the size increases, but rather that > labels go from purely source syntax to an ABI. I'd rather see some > decision as to which labels are enabled or not." > > And then I learned with hints from Rob and Geert that symbols are not > really necessary for overlays, you just cannot use named labels. But > using > > target-path = "/soc/i2c@23473245"; > > or > > target = <&{/soc/i2c@23473245}>; > > instead of > > target = <&i2c1>; > > works fine. (And if you need to add a phandle the &{/path/to/node} > construct should work, too (but I didn't test).) Using labels is a tad nicer, but the problem I wanted to address with my patch now has a known different solution. > > Best regards > Uwe > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >
