Hi Frank, On Wed, Sep 5, 2018 at 10:54 PM Frank Rowand <frowand.list@xxxxxxxxx> wrote: > On 09/04/18 01:27, Tero Kristo wrote: > > Add support for TI specific DT subdir, along with support for building > > DT overlays. Right now, no DT files are specified in this directory, > > those are to be added later. > > > > Signed-off-by: Tero Kristo <t-kristo@xxxxxx> > > --- /dev/null > > +++ b/arch/arm/boot/dts/ti/Makefile > > @@ -0,0 +1,9 @@ > > +# SPDX-License-Identifier: GPL-2.0 > > +# > > +# Make file to build device tree binaries for boards based on > > +# Texas Instruments Inc processors > > +# > > +# Copyright (C) 2016-2018 Texas Instruments Incorporated - http://www.ti.com/ > > +# > > + > > +DTC_FLAGS += -@ > > > > I will nack any attempt to unconditionally compile a devicetree file with the > -@ flag (which adds symbols to the resulting .dtb). The resulting overhead > is not acceptable. > > Adding the symbols must be under the control of the person either creating > or using the .dtb. The way to provide that control is the challenging part. > > One way would be to configure the compile option via kbuild configuration. > There is opposition to this approach because it makes the .dtb dependent > on the Linux kernel configuration. So suggestions of an alternative > mechanism would be welcome. IMHO that would be quite a "soft" dependency: it's just about adding symbols or not. No real dependency on Linux or kernel features. > Another _possible_ solution would be to add a dtc_strip tool to the dtc > project. dtc_strip would remove the symbol information from a .dtb, > in a manner that is analogous to strip removing debug information from > a program file. Removing unwanted symbols is indeed easier than adding them to an existing DTB. > One aspect of unconditionally building a .dtb with symbols, then > optionally removing the symbols with dtc_strip is that it seems > like a backwards process. For example, we don't build the kernel > with debug symbols then strip the symbols out when we don't want > them. I'll have to mull this over if the dtc_strip method sounds > like a good approach to other people. That's not a fair comparison: DTB symbols are not debug information, but an ABI. It's more akin to exporting kernel symbols to (possible out-of-tree) kernel modules, which is controlled by CONFIG_MODULES. So a Kconfig symbol to enable it, and a dtc_strip for removing them, makes most sense to me. BTW, we do run strip on vmlinux ;-) Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
