[U-Boot] [PATCH] Introduce a new linker flag LDFLAGS_FINAL

[Scott Wood]

On Tue, 1 Feb 2011 21:20:50 +0100
Wolfgang Denk <wd at denx.de> wrote:

> Dear Scott Wood,
> 
> In message <20110201135136.0817fe5a at udp111988uds.am.freescale.net> you wrote:
> >
> > > > Prior to the introduction of LDFLAGS_u-boot, was LDFLAGS not what was
> > > > used?  So before, anything that board/cpu code adds directly to LDFLAGS
> > > > (maybe they're supposed to use PLATFORM_LDFLAGS, but not all do) was
> > > > used in the final link.  After 8aba9dc, only things in
> > > > PLATFORM_LDFLAGS plus -Bstatic and -T are used in the final link.
> > > 
> > > And this is correct for all boards?
> > 
> > By "this" do you mean the switch to PLATFORM_LDFLAGS in 8aba9dc, or the
> > switch back to LDFLAGS?  It's not obvious to me that the dropping of
> 
> I don;t understand why you contine to talk about "switch to
> PLATFORM_LDFLAGS in 8aba9dc".  There was no such switch - at least I
> cannot see it.
> 
> I see only a switch in your patch.  This is why I'm asking.

Before 8aba9dc, the flags for the final link were produced by taking
the existing LDFLAGS, and adding:
-Bstatic -T <linkerscript> $(PLATFORM_LDFLAGS) -Ttext <addr>.

This included anything that cpu/board code added to LDFLAGS -- some
architectures added --gc-sections, x86 added --cref, etc.  Since the above
flags are added to LDFLAGS, rather than replacing them, these flags got used
in the final link.

Commit 8aba9dc introduces LDFLAGS_u-boot, so that LDFLAGS is no longer the
source for the flags for the final link.  It generates LDFLAGS_u-boot using
PLATFORM_LDFLAGS, not LDFLAGS.  It converts most of the board/cpu updates to
LDFLAGS into LDFLAGS_u-boot, but it missed --cref.

I don't see any other LDFLAGS changes in board/cpu code, so the distinction
between using LDFLAGS and PLATFORM_LDFLAGS should have no other impact on
current boards.  However, the patch appears to be intended to support
platform linker flags that need to be used during partial link, which
would involve board/cpu additions to LDFLAGS.  This change would break that
only if those options need to be used for partial link *only*, and cannot be
used in the final link.  In such a case I'd suggest using something like
LDFLAGS_PARTIAL to make this explicit.  But I'd be surprised if that
were actually the case.

If you're looking to cut down on the number of variables, it's not clear to
me what PLATFORM_LDFLAGS is supposed to mean distinct from adding to
LDFLAGS.

-Scott