[PATCH] ARM: Remove kernel booting call for thumb2 mode

[Sascha Hauer]

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 |