+Stephen who will know more Hi,
On 13 February 2016 at 18:52, quantumlight <peter.feifan.c...@gmail.com> wrote: > I am trying to modify the bootloader code for NVIDIA's jetson board. > > So I am looking at crt0.S. It seems that two builds happen, one with > CONFIG_SPL_BUILD and one without. So you end up with two file, u-boot.bin > and spl/u-boot-spl.bin. SPL is built with ARMv4t U-Boot proper is built with ARMv7 That's why SPL is used on Tegra. The SPL does not actually load U-Boot. In fact both are bundle together and loaded at the same time. SPL simply jumps to U-Boot when needed. > > However, I am unable to find the code path that calls board_init_r() after > board_init_f() finishes, although there are several candidates: > > 1) crt0.S - if CONFIG_SPL_BUILD was not defined, then it would fall straight > through to board_init_r() - HOWEVER, for u-boot.bin, isn't CONFIG_SPL_BUILD > defined in autoconf.h? Or is this some clever magic between how u-boot.bin > and spl/u-boot-spl.bin are stitched together? For U-Boot, CONFIG_SPL_BUILD is not defined. That define means you are building SPL. The clever magic is mostly 'cat'. SPL is padded a little and then U-Boot is added on the end. > 2) _weak board_init_f in arch/arm/lib/spl.c - HOWEVER, shouldn't this be > overloaded by board_init_f in common/board_f.c? The latter is only used in U-Boot proper. SPL has its own board_init_f(). > 3) board_init_f_r in common/board_f.c - HOWEVER, nothing calls > board_init_f_r(). No, that is not used on ARM. > > Can someone illuminate me on how this happens? > See the README under Board Initialisation Flow. In brief, the link between board_init_f() and board_init_r() is generally the crt0.S that you found. The catch is that some boards don't implement board_init_f() in SPL, and so use the weak one, which in fact calls board_init_r() directly. See also arch/arm/mach-tegra/board.c which I think contains the code to jump to SPL. Regards, Simon _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
