[U-Boot] [PATCH 6/6] ARM: rmobile: Sync Gen3 defconfigs

[Eugeniu Rosca]

cc: Masahiro (due to Kconfig topic)

Hi Marek,

On Mon, Mar 04, 2019 at 11:03:56PM +0100, Marek Vasut wrote:
> On 3/4/19 10:36 PM, Eugeniu Rosca wrote:
> > Hello Marek,

<-snip->

> > Do you think it would make sense to relocate the common parts into
> > rcar{3,-gen3}_defconfig and the unique per-board options into config
> > fragments resembling the current R-Car3 defconfig structure?
> > 
> > $> u-boot-master (master) ls -1 configs/r8a779* | sed 's/_defconfig/.cfg/'
> > configs/r8a7795_salvator-x.cfg
> > configs/r8a7795_ulcb.cfg
> > configs/r8a77965_salvator-x.cfg
> > configs/r8a7796_salvator-x.cfg
> > configs/r8a7796_ulcb.cfg
> > configs/r8a77970_eagle.cfg
> > configs/r8a77990_ebisu.cfg
> > configs/r8a77995_draak.cfg
> > 
> > In this case, I believe each fragment would contain under 10 Kconfig
> > symbols and the `make <board>_defconfig` procedure would change
> > to `make rcar{3,-gen3}_defconfig <board>.cfg`.
> 
> I was pondering whether there's some way to factor out the common parts,
> or maybe even replace some of the defconfigs with a placeholder for
> compatibility reasons and just go with one full defconfig for all SoCs
> (H3/M3W/M3N) that can be on such a board.
> 
> I'd still like to be able to do "make soc_board_defconfig ; make"
> without having to rack my brain which other .cfg files I need to append.
> I didn't find a good solution for this however. Do you know of one ?

I think we have proper tools to track the correctness of the defconfig
files (i.e. savedefconfig Kbuild target), but we don't seem to have
proper tools to validate configuration fragments. So, I agree the
contents of the fragments would potentially go wild. I think having
either a built-in Kbuild/Kconfig procedure or some scripted way to keep
the fragments under control would greatly increase the confidence in
using them, but I am unaware of such.

JFTR, rcar-3.9.3.rc1 U-Boot has double the amount of vanilla R-Car3
defconfigs:

$> u-boot (rcar-3.9.3.rc1) ls -1 configs/r8a779*
configs/r8a7795_salvator-x_defconfig
configs/r8a7795_salvator-xs-2x2g_defconfig
configs/r8a7795_salvator-xs-4x2g_defconfig
configs/r8a7795_salvator-xs_defconfig
configs/r8a7795_ulcb-4x2g_defconfig
configs/r8a7795_ulcb_defconfig
configs/r8a77965_salvator-x_defconfig
configs/r8a77965_salvator-xs_defconfig
configs/r8a77965_ulcb_defconfig
configs/r8a7796_salvator-x_defconfig
configs/r8a7796_salvator-xs_defconfig
configs/r8a7796_ulcb_defconfig
configs/r8a77970_eagle_defconfig
configs/r8a77990_ebisu-4d_defconfig
configs/r8a77990_ebisu_defconfig
configs/r8a77995_draak_defconfig

So, changing/adding/removing a common option (most of them are) implies
quite an amount of maintenance effort on our side. I would greatly
appreciate any ideas how to alleviate that.

> 
> -- 
> Best regards,
> Marek Vasut

Best regards,
Eugeniu.