> Sascha, > On 24 Feb 2012, at 07:23, Sascha Hauer wrote: > >> Hi Mark, >> >> On Thu, Feb 23, 2012 at 04:53:28PM +0000, Mark Olleson wrote: >>> omap4_bootsrc() always returns OMAP_BOOTSRC_UNKNOWN when an OMAP4 >>> xload image is built with pcm049_xload_defconfig. This is likely to >>> be the case for all OMAP4 xload configurations. >>> >>> This means that when the CPU is configured to boot from MMC1 with >>> boot[5:0], xload will load the second stage boot loader from NAND >>> flash (if present) rather than MMC1 as intended. >>> >>> omap4_bootsrc() reads data left behind towards the top of the SRAM by >>> the ROM-based boot-loader. This is the same SRAM into which the xload >>> image is loaded. The xload image is of a sufficient size that it >>> overwrites these locations, and OMAP4_TRACING_VECTOR3 always contains >>> 0. >>> >>> These locations are in fact trampled by data in the BSS section of the >>> image. The single largest item in there is FILE files[MAX_FILES]. >>> This patch reduces the size of files[] considerably. The image now >>> JUST fits. >> >> Sorry, this is not even a short term solution, it will probably break >> very soon again. > > I totally agree - this fixed me in the very short term, but we're sailing so close > to the wind here that changes in the any (few) modules that are used in these > configurations will break it again. > > My patch was really a heads-up that we have an issue. > >> On further digging, this gets even worse: Barebox's initial stack is in the same area of SRAM as the ROM-loader's - overwriting the area where bss section of the image is getting loaded, containing various areas of static storage. Here, these addresses were falling somewhere in the middles of: static FILE files[MAX_FILES] Thankfully, there isn't a great deal of function call depth before the stack is then set up in SDRAM, and tramples here don't matter too much. Anyway, be warned - some interesting failure modes lie ahead should some of the other bits of static data or even program code fall at this location! Mark --- Mark Olleson - Senior R&D Engineer Technology Research & Development Group Yamaha R&D Centre London mark.olleson@xxxxxxxxxxxx _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
