On Thu, Dec 03, 2015 at 01:24:56AM +0000, Trent Piepho wrote: > The asm code to do the actual call into the kernel (or another > barebox) when compiled in thumb2 mode isn't necessary. gcc generates > a perfectly good calling sequence from a normal function pointer call. > If it didn't, the code in bootstrap_boot() that uses a function > pointer to jump to the 2nd stage barebox from an xloader wouldn't > work. > > It appears to be allowed that the call to kernel() could return, as > neither start_linux() nor kernel() are marked noreturn, and there is > code after calls to start_linux(). > > The asm code has a bug in this case, as it uses bx and not blx, and > thus doesn't set the link register. Since it's a tail call, this > would be okay, but only if the LR value from the start of > start_linux() (and the callee-saved registers) are restored > beforehand, which isn't done. The gcc generated call sequence will do > this. The kernel won't return, so this bug shouldn't hit us. Anyway, nice cleanup. Tested and applied, thanks 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
