On 5/26/20 1:58 PM, Anatolij Gustschin wrote:
On Tue, 26 May 2020 13:25:00 +0200 Marek Vasut marex@denx.de wrote:
On 5/26/20 1:12 PM, Soeren Moch wrote:
On 25.05.20 22:24, Anatolij Gustschin wrote:
Converting to DM increases binary size and breaks building some boards (i.e. tbs2910, gcc 9.2). The approach to address this issue via cutting off unused properties/nodes in device tree via custom u-boot.dtsi was not welcome, even if the affected boards do not pass the built-in device tree to the kernel.
But there is CONFIG_OF_REMOVE_PROPS="dmas dma-names interrupt-parent interrupts interrupts-extended interrupt-names interrupt-map interrupt-map-mask" in tbs2910_defconfig. So removing properties is already done via this config option. Removing nodes is not implemented (yet? AFAIK). But would be welcome if someone implements this in a similar way, I think.
Why don't we turn this the other way around -- put the { compat string , driver } tuple list into a U-Boot linker list, then filter this linker list against a DT which will be used for the platform (what if there are multiple DTs?), and then scrub all unreferrenced symbols.
This might be a topic again when new bloat causes build breakage again. For now I've succeeded to build the tbs2910 board with default CI tool chain without this patch (by making DM_VIDEO parts optional). Stripping unused compatible entries doesn't save much here (around 800 bytes). So the question is if it is worth the effort to implement such scrubbing.
It is if you can remove all the unused compatibles and all the data/rodata they reference. I think it would be nice to prototype this at least and see how much this really saves. I suspect for SPL this might be interesting even more.