Sashca, On 4/23/2010 6:03 PM, Sascha Hauer wrote:
Lets translate the startup code to a language we all understand better. Tested on pcm038 (arm v5) and pcm043 (arm v6). Signed-off-by: Sascha Hauer<s.hauer@xxxxxxxxxxxxxx> --- arch/arm/cpu/Makefile | 6 +- arch/arm/cpu/start-arm.S | 248 ------------------------------------ arch/arm/cpu/start.c | 107 ++++++++++++++++ arch/arm/include/asm/barebox-arm.h | 3 + arch/arm/lib/barebox.lds.S | 2 +- 5 files changed, 112 insertions(+), 254 deletions(-) delete mode 100644 arch/arm/cpu/start-arm.S create mode 100644 arch/arm/cpu/start.c
Some random comments: * Even though I'm an ARM newbie, but with some training I've found that the existing startup code originating from U-Boot is reasonably simple and easy to read. Current code is not as bad as you ARM experts feel it is ;-) * I also agree that C version tells us a lot nicer than aseemblers about what's going on in the sequence, especially board_init_lowlevel_return() part looks quite easy-to-follow. * That said, I don't think implementing startup code using inline assemblers _with_Extended_ASM_ is easy to maintain. Are you really happy with such core parts implemented in 'C'? This patch has proved that we could write even the startup seq- ences with 'C' (with extended asm.), but that doesn't necessarily means that's the way to go. * I don't think that all startup sequences necessarily need to be impelmented in 'C'. Board_init_lowlevel() is worth trying 'C' as it does a bunch of machine-specific register operations, which are easy-to-follow if they're implemented in 'C'. Patch 12/14 and 14/14 look very nice! Board_init_lowlevel_return() is also worth trying as well. However, having ASM and C code for the startup sequences might be slightly a mess, hmm. * Leaving good comments, for example describing C version of start- up code somewhere in the tree, might suffice. Note that I'm not objecting these changes. I'm all for your changes in the project, especially on steering ARM area. -- Shinya Kuribayashi Renesas Electronics _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
