Re: [PATCH] cmd_dtc: Enable generation of device tree symbols
From: Rob Herring <robh@kernel.org>
Date: 2021-01-26 13:45:09
Also in:
linux-devicetree, linux-kbuild, lkml
On Tue, Jan 26, 2021 at 1:27 AM Uwe Kleine-König [off-list ref] wrote:
Hello Masahiro, On 1/25/21 10:53 PM, Masahiro Yamada wrote:quoted
On Mon, Jan 25, 2021 at 8:07 PM Uwe Kleine-König [off-list ref] wrote:quoted
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 <redacted>(CCing DT ML.)makes sense, thanks.quoted
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."
I've also said move the arm32 dts files to family subdirectories and enable '-@' per directory. I've posted a script to do the whole thing, but I think the preference is one-by-one. This is needed anyways if we're going to start adding overlays which Viresh is working on. Rob _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel