[U-Boot] [PATCH] tegra20: add back USE_PRIVATE_LIBGCC

[Allen Martin]

On Tue, Aug 07, 2012 at 10:09:00AM -0700, Lucas Stach wrote:
> Am Dienstag, den 07.08.2012, 11:00 -0600 schrieb Stephen Warren:
> > On 08/06/2012 06:19 PM, Lucas Stach wrote:
> > > As discussed here [http://patchwork.ozlabs.org/patch/158202/] we want to
> > > use USE_PRIVATE_LIBGCC still.
> > > 
> > > However commit 5286f1ce dropped it regardless. Adding this back fixes a
> > > hang while handing over from SPL to U-Boot on Colibri T20.
> > 
> > This probably makes sense, but Allen should comment on this.
> > 
> > I wonder why I haven't seen any issue with this; perhaps SPL on all the
> > boards I tested ended up not using any libgcc functions? But in that
> > case, why would the Colibri board end up using them?
> > 
> Could also be a toolchain issue. My normal workflow uses a toolchain
> without a libgcc, as we didn't needed it to this point.
> After porting over my changes to the new SPL boot I had to switch to a
> CodeSourcery toolchain containing a libgcc. So I'm not entirely sure
> where the problem lies, as I varied codebase and toolchain at one. But I
> confirmed that this patch works with both of my toolchains.
> 
> So yes, I'm really in favour of some comments.

What's the CodeSourcery toolchain you're using?  The
USE_PRIVATE_LIBGCC was used to prevent armv5 instructions from the
toolchain's libgcc from getting into the code that executes on the AVP
which is an arm7tdmi (armv4t).  Since all the code that runs on the
AVP is built separately now as part of the SPL, using the toolchain's
libgcc should work for the main u-boot build.  USE_PRIVATE_LIBGCC is
still turned on for the SPL build.

I've tested the following toolchains on ventana and seaboard tegra20
platforms:

gcc 4.4.6 arm7tdmi-linux-gnueabi built with crosstool-ng
gcc 4.4.6 cortex_a9-linux-gnueabi built with crosstool-ng
gcc 4.6.1 cortex_a9-linux-gnueabi built with crosstool-ng

Tell me what CodeSourcery version you're using and I'll test it here
as well and see if I can reproduce the problem.

-Allen
-- 
nvpublic