Hi James, On Saturday 04 June 2016 12:25 AM, James Pollard wrote: > Hi, > > I'm a new U-Boot user. I'm trying to follow the flow of execution for the > ARMv7 architecture, and have found myself running into confusion. > > At the end of arch/arm/cpu/armv7/start.S, lowlevel_init is called. This is > defined (for the ARMv7 architecture in arch/arm/cpu/armv7/low_level_init.S > (not sure if there's a reason for the discrepancy in the use of > underscores?), and at the end of this file, s_init is called.
So, s_init is called by cpu_init_crit and after that _main will be called. Below is the code flow for u-boot(Skipped all the #ifdefs). - reset - save_boot_params - cpu_init_cp15: - Invalidate caches and apply erratas: - cpu_init_crit: - lowlevel_init - s_init - _main (arch/arm/lib/crt0.S) - Setup C runtime environment - board_init_f - relocate code if !SPL - board_init_r > > As far as I can tell, s_init is only defined for some of the ARMv7 CPUs: > the bcm281xx folder doesn't contain any files that define this function. In > the case of the am33xx CPU it's defined in board.c, but this function seems > to return without calling board_init_f. s_init is not necessary to be called for all the boards. board_init_f should take care of system init. As per the above code flow board_init_f will be called for every board. > > My questions are: > > 1. In the case of the bcm281xx, what happens? s_init doesn't seem to be > defined for this CPU. Yes, board_init_f will take care of the initialization. > 2. In the case of the am33xx, where is board_init_f called? As far as I > can tell, s_init should return to lowlevel_init without having > called board_init_f , which then returns back to start.S, terminating > the execution prematurely. This has been answered above. > > I presume my analysis of the assembly must be highly incorrect? > > Sorry if this is the wrong place for such a question. Yes, this is the right place to ask :) Thanks and regards, Lokesh > > Yours, > > James Pollard > _______________________________________________ > 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