Re: [PATCH 0/5] ARM: orion5x/dove/mv78xx0 multiplatform

Arnd Bergmann
2015-12-10T21:30:30Z

On Thursday 10 December 2015 22:14:25 Detlef Vollmann wrote:
> On 12/10/15 21:59, Arnd Bergmann wrote:
> > On Thursday 10 December 2015 20:03:18 Detlef Vollmann wrote:
> >> On 12/10/15 14:43, Arnd Bergmann wrote:
> >>> text data bss dec hex filename
> >>> 942144 64112 17648 1023904 f9fa0 build/tmp/vmlinux-orion-allno
> >>> 1027516 54052 20824 1102392 10d238 build/tmp/vmlinux-multi-plus-orion
> >>> 1025320 66020 18744 1110084 10f044 build/tmp/vmlinux-orion-plus-of
> >>>
> >>> The diff below shows all the differences between orion-allno and
> >>> multi-plus-orion.
> >> How did you get the orion-allno config and how did you get it compiled?
> >> I tried to apply your changes to my config and compile it, but
> >> it started silentoldconfig which introduced back 'ARCH_MULTIPLATFORM'
> >
> > The first and third row are without my patches, once they are applied,
> > ARCH_ORION becomes a sub-option of ARCH_MULTIPLATFORM.
>
> So with your patches it's no longer possible to build a small kernel, correct?

Correct. I was a bit surprised at how much object code enabling CONFIG_OF
adds these days, it used to be a lot less, but you are right that
disabling CONFIG_OF is not possible with the way that ARCH_MULTIPLATFORM
is structured.

It was always the plan to move all orion5x machines over to use CONFIG_OF
eventually, so you get that overhead one way or another, and at least
it looks like doing multiplatform on top of OF doesn't add any noticeable
extra overhead (the total numbers are actually smaller).

It may also be worth investigating what has made CONFIG_OF so costly,
maybe we can reduce this a bit again.

Arnd