[U-Boot] [PATCH] spl: remove forced linking of commands into SPL

[Tom Rini]

On Thu, Aug 09, 2012 at 10:37:43AM -0700, Tyler Olmstead wrote:
> Hi Tom,
> 
> On Thu, Aug 9, 2012 at 7:35 AM, Tom Rini <trini at ti.com> wrote:
> > On 08/08/2012 07:24 PM, Tyler Olmstead wrote:
> >
> >> Remove linker command line options from the SPL makefile
> >> that force the inclusion of unreferenced command code from
> >> linked object files. As commands are not used in the SPL,
> >> these options resulted in an unnecessary increase in the
> >> image size, in addition to introducing the possibility of
> >> tricky link errors in the case where the command code
> >> contained symbols that were not resolved by linking in the
> >> limited objects compiled in the SPL build.
> >>
> >> Signed-off-by: Tyler Olmstead <tyler.j.olmstead at gmail.com>
> >
> > Without either figuring out how to make the strings be garbage collected
> > automatically (I'm talking with a toolchain friend of mine about how to
> > try and do this) or whacking U_BOOT_CMD to do this for us, we will start
> > adding bloat to SPL after we do this.
> >
> 
> I absolutely agree that bloat in the SPL should be avoided wherever
> possible, but I don't understand how this patch would increase the
> image size by *not* forcing commands to be linked in. There are
> numerous examples where the linker is relied upon to not include
> unused code into SPL. Is there something unique about U_BOOT_CMD that
> makes it especially troublesome?

It doesn't bloat today, true.  It bloats as soon as someone else adds in
code that links in a new U_BOOT_CMD that wasn't guarded as now the
string literals that before would have been guarded and not linked in
will now be un-guarded and not garbage collected (while the command will
be).  The linker is in fact getting this wrong already in a number of
cases (run a 'strings' on an SPL binary) and this needs to be fixed too.
I don't want to make the problem potentially worse until we have a fix
for the general problem.

To see what I mean, build omap3_beagle with this patch and then un-guard
nandecc in arch/arm/cpu/armv7/omap3/board.c.  The command will be
collected but the command/help string will be in the binary.

-- 
Tom