[U-Boot] [PATCH 3/3] powerpc, 8xx: adapt a few linker scripts so it will build.

[Joakim Tjernlund]

Wolfgang Denk <wd at denx.de> wrote on 2011/04/25 10:35:25:
>
> Dear Joakim Tjernlund,
>
> In message <OF102CC99D.B86B21B6-ONC125787C.007CB439-C125787C.0080F875 at transmode.se> you wrote:
> >
> > Well, your gcc is different from mine and I know nothing about it as
> > you won't say anything about it.
>
> If in doubt, use ELDK.  All examples were compiled with ELDK 4.2 (GCC
> 4.2.2) for ppc_8xx.

Have you tried gcc 4.3.x yet?

>
> > ## 4.4.5 has been patched to support msingle-pic-base
> > CROSS_COMPILE=powerpc-4.4.5_softfloat-linux-gnu- ./MAKEALL  TQM855L TQM860L
> > Configuring for TQM855L board...
> >    text      data       bss       dec       hex   filename
> >  267022      5284     27200    299506     491f2   ./u-boot
> > Configuring for TQM860L board...
> >    text      data       bss       dec       hex   filename
> >  267043      5284     27200    299527     49207   ./u-boot
>
> I don't have gcc 4.4.x here for testing.
>
> > So I strongly suspect that as soon as you move your gcc version upwards, it will break
> > these boards too.
>
> Yes, but for other reasons.

Rather for these reasons too :)

>
> Recent versions of GCC (gcc 4.5.x) cannot be used to build this code
> at all until they get fixed, as -Os is not working, and the code size
> explodes completely. See GCC bugs 43810, 48278, and 45053.

hmm, can't really make out if these TR:s also applies for gcc 4.4.5?
There are some hints but I cannot tell for sure.

>
> > > I will not apply either of these commits - neither the reverted one,
> > > nor this additional one, as both of them grow the memory footprint
> > > instead of redusing it as you promised in the commit message.
> >
> > You should read the commit msg again. It requires a gcc which
> > supports -msingle-pic-base.
>
> As the majority of gcc versions outthere does not support this
> feature, we are trading a (slight?) advantage for a very limited group
> against disadvantages for a very large group (probably everyone else
> but you).

That will probably change very soon. Gentoo will have -msingle-pic-base
in its next gcc bump of 4.4.x and 4.5.x

I think the mistake was to include the use of -fno-jump-tables in that
patch too. The -msingle-pic-base part should be a NOP to all gcc's that
don't have it.

>
> > I still don't know why it broke with your gcc but I suspect
> > it is due to -fno-jump-tables(which is in the msingle-pic-base patch).
> > Seems like that option in your case makes the code bigger.
>
> Indeed. As I cannot see any advantages, I reject this stuff, at least
> for now.

Indeed? Does that mean you confirmed that -fno-jump-tables was the cause?
I can respin the patch without that part if so.

 Jocke