Hi Giorgio, On Tue, Feb 13, 2018 at 11:12:54PM +0100, Giorgio Dal Molin wrote: > Hi all, > > I'm trying to add board code for an am335x based HW project. > I had a look at similar boards like 'boards/phytec-som-am335x' > or 'boards/beaglebone'. > I understand that I need two images: the (little) MLO and the > (bigger) barebox. > > What it's not really clear is how the MLO loads and starts the > barebox. See arch/arm/mach-omap/xload.c. It is compiled when no shell is enabled (I think at least for clarity there should be a separate Kconfig symbol). In this file omap_xload() detects where the SoC has booted from and loads the full barebox from the same source. > > Moreover I saw there's always a call to: > > am33xx_save_bootinfo((void *)bootinfo); > > in the MLO lowlevel entry function; I suspect the argument > 'bootinfo' is the register r0 left by the function __barebox_arm_head() > but I cannot really understand the logic behind it. When the am335x ROM passes control to the bootloader then it passes in R0 a pointer to the bootinfo. This is a three word structure which has informations where the SoC has booted from. In am33xx_save_bootinfo() we copy the information to a known place where we can pick it up later, see am33xx_bootsource(). Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
