Re: [PATCH 1/5] kbuild: thin archives final link close --whole-archives option

[Nicholas Piggin <npiggin@gmail.com>]

On Wed, 21 Jun 2017 13:32:17 +0200
Arnd Bergmann <arnd@arndb.de> wrote:

> On Wed, Jun 21, 2017 at 1:10 PM, Nicholas Piggin <npiggin@gmail.com> wrote:
> > On Wed, 21 Jun 2017 12:49:10 +0200
> > Arnd Bergmann <arnd@arndb.de> wrote:
> >  
> >> On Wed, Jun 21, 2017 at 12:38 PM, Nicholas Piggin <npiggin@gmail.com> wrote:  
> >> > On Wed, 21 Jun 2017 12:21:16 +0200
> >> > Arnd Bergmann <arnd@arndb.de> wrote:
> >> >  
> >>
> >> I'm building on top of yesterday's linux-next at the moment,
> >> with a number of my own patches applied
> >>  
> >> > I can take a look at ARM and try to get it at least to parity with
> >> > incremental link. Any particular config options required?  
> >>
> >> This is the patch I am testing with:
> >>
> >> https://pastebin.com/HQuhCEmK
> >> I have not looked at that in a while, no idea if it works, or
> >> if it has known problems.
> >>
> >> I last posted the patch in March for discussion:
> >>
> >> https://patchwork.kernel.org/patch/9626207/  
> >
> > Well I just mean the stuff now in kbuild/thin-ac, not the LD_DCDE.
> > Just want to try getting thin archives up to a point where there are
> > no serious regressions first.  
> 
> For my build testing, I have now reverted most of my patch and only
> left the 'select THIN_ARCHIVES'. I'll let you know if I run into problems.

Okay. Currently with the patches in the kbuild tree, thin archives
actually does better than incremental linking for ARM (defconfig).

11651574	6090952	 418616	18161142	1151df6	vmlinux.thinarc
11656118	6095208	 418952	18170278	11541a6	vmlinux.inc

In mainline, thin archives is sub-optimal for lib-y libraries (just
pulls them all in). But now that I test it, even that is better than
incremental linking for ARM:

11653926	6090888	 418620	18163434	11526ea	vmlinux.thinarc

I haven't grabbed that "clk: sunxi-ng: Move all clock types to a library"
patch yet to check. What tree is it in? I wonder if I could convince you
to drop that for now and bring it up on linux-kernel/linux-kbuild? I
think it's quite reasonable to reduce Kconfig hell of very fine grained
conditional compilation/linking if we can make the toolchain do it for
us. So we should consider how to support it nicely rather than having
such hacks IMO.

Thanks,
Nick