Re: [PATCH] kbuild: provide THIN_ARCHIVES option for all architectures

[Nicholas Piggin <npiggin@gmail.com>]

On Mon, 29 May 2017 20:22:41 -0700
Linus Torvalds <torvalds@linux-foundation.org> wrote:

> On Mon, May 29, 2017 at 4:13 PM, Nicholas Piggin <npiggin@gmail.com> wrote:
> >
> > *thin* archives does require binutils 2.19. That's nearly 10 years
> > old, but we advertise 2.12 minimum at the moment.  
> 
> I think we're ok with upgrading that. We've been allowing some
> ridiculously old tools at times. I think "feature is 10 years old and
> actively used by other projects" (Qt uses it from some googling, for
> example) is more than sufficient.

Well we might have to. I couldn't make thick archives work easily
because we have multiple levels of built-in.o, and with thick you
get an archive of an archive which the linker does not understand.
Fixing that would mean unpacking the archive and repacking it for
every built-in.o input you link -- too painful.

I suspect Google uses the format internally too because they added
the initial support.

https://sourceware.org/ml/binutils/2008-03/msg00150.html

Support has been pervasively added to binutils -- nm, objdump, ld,
etc. I think it falls into the category of well supported.

> 
> If somebody has user space older than that, they presumably aren't
> building new kernels either.

Yeah I think it's reasonable to drop support for such old toolchain
if we have a reason for it.

I'll send a patch to 0day and if that passes, I'll see if it's
something Stephen would put into linux-next.

Thanks,
Nick