Hi Andrew, On Sun, 2010-09-12 at 21:00 -0500, Andrew Dyer wrote: > On Sun, Sep 12, 2010 at 17:38, Peter Tyser <pty...@xes-inc.com> wrote: > > Using -fno-toplevel-reorder causes gcc to not reorder functions. This > > ensures that an application's entry point will be the first function in > > the application's source file. > > > > This change, along with commit 620bbba524fbaa26971a5004793010b169824f1b > > should cause a standalone application's entry point to be at the base of > > the compiled binary. Previously, the entry point could change depending > > on gcc version and flags. > > > > Note -fno-toplevel-reorder is only available in gcc version 4.2 or > > greater. > > > > Signed-off-by: Peter Tyser <pty...@xes-inc.com> > > --- > > I didn't have a version of gcc < 4.2. The change is pretty trivial so > > it should work, but it'd be appreciated if someone with an old toolchain > > installed could give the patch a shot. > > > > Since I was writing a standalone test program today, I manually tested > against an older u-boot and arm gcc 4.4.1. Worked fine. You can add > my tested-by if you feel that's sufficient. > I wonder if this is the right way to fix this. It seems a bit subtle. > I thought of two other possible workarounds - have the Makefile use > mkimage as part of the output so the entry point is embedded in the > mkimage file, or redo the programs to have a main() as entry and write > a crt0.S equivalent and have the entry location for that fixed in a > linker file.
Thanks for testing. I agree this isn't the most elegant solution, but its one big advantage is simplicity in my mind. Creating/maintaining a crt0.S and/or link script for each CPU architecture seems like overkill for a simple (deprecated?) application interface to me. I was under the impression the preferred application interface going forward was the one enabled by CONFIG_API in examples/api. It uses the crt0 solution, but only supports ppc and arm right now. Using a uImage format for apps seems like a fine solution too. Do others have a preference? I agree we should be using main() as the entry point either way. I'll add that to the TODO list. If we did go with -fno-toplevel-reorder I could add the following to each application to make it clear what's going on: /* Define main() protoype first to ensure its the first function in the image */ int main(int argc, char * const argv[]); Best, Peter _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
