Hi Uwe, On 1/26/21 12:03 PM, Frank Rowand wrote: > +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:. Unfortunately I have not been on irc recently (now rectified). Do you perchance have a copy of the irc conversation that you can send me? (No need to edit out unrelated messages, a simple cut and paste from the start of the conversation to the end is fine.) -Frank >> >> 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 >> >
