On Wed, Apr 20, 2011 at 11:56 PM, Aneesh V <ane...@ti.com> wrote: > Hi Simon, Wolfgang, > > On Thursday 21 April 2011 12:04 AM, Simon Glass wrote: >> >> On Fri, Mar 25, 2011 at 11:35 AM, Albert ARIBAUD<albert.arib...@free.fr> >> wrote: >>> >>> Le 25/03/2011 17:12, Aneesh V a écrit : >>> >>>> Another problem I have with relocation is that it makes debugging with >>>> JTAG debugers more difficult. The addresses of symbols in the ELF >>>> target are no longer valid. Of course, you can load the symbols at an >>>> offset from the original location. But one has to first enable debug >>>> prints, find the relocation offset, use it while loading the symbols >>>> before you can do source level debugging. >>> >>> Actually you don't need recompiling: simply set a breakpoint at the >>> entry of relocate_code and once you hit the bp, look up r2: it contains >>> the destination. If you want the offset rather than the absolute >>> address, set the breakpoint right after the 'sub r9, r6, r0' round line >>> 222: r9 will then give you the offset. Unload the current symbols, >>> reload the symbols with the relevant offset, and there you go. >> >> I would like to revisit this thread. I'm not sure how other people do >> development in U-Boot but I like to use an ICE and a source-level >> debugger for any significant effort. I think it should be possible to >> use a JTAG debugging just by loading the u-boot ELF file and running. >> >> With this patch (or something similar) this is possible. Without it, >> it is painful. >> >> To be clear, we are not talking here about creating a platform that >> doesn't use relocation, just that for development purposes it is >> convenient to be able to disable it. > > Actually, I am not even sure why relocation shouldn't be disabled in my > platform for good. It may be useful to have things such as the frame > buffer at the end of available memory. But, IMHO, that can still be > done without relocating u-boot. That's what the patch does.Am I missing > something?
Well relocation does remove a lot of this ad-hoc positioning of things at compile time. I think it is desirable. My point is that it is not engineer-friendly during development, and we should have an easy way to disable it for debugging / JTAG purposes. Regards, Simon > >> >> Looking at the December thread >> http://thread.gmane.org/gmane.comp.boot-loaders.u-boot/88067/focus=88262 >> >> Aneesh: >>>> >>>> Shouldn't we provide a CONFIG option by which users can disable >>>> Elf relocation? >> >> Wolfgang: >>> >>> Why should we? It would just make the code even more complicated, and >>> require a lot of additional test cases. >> >> From what I can see this is a new CONFIG option, two ifdefs in the >> board.c file, and optionally disabling the -pie position-independent >> executable option to reduce size. It is pretty trivial: >> >> arch/arm/config.mk | 2 ++ >> arch/arm/lib/board.c | 5 +++++ >> 2 files changed, 7 insertions(+), 0 deletions(-) >> >> Regards, >> Simon >> >>> >>> Amicalement, >>> -- >>> Albert. >>> _______________________________________________ >>> U-Boot mailing list >>> U-Boot@lists.denx.de >>> http://lists.denx.de/mailman/listinfo/u-boot >>> > _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
