[U-Boot] [U-Boot, v7, 2/2] arm: move gd handling outside of C code

[Tom Rini]

On Thu, Jan 14, 2016 at 12:27:02PM -0700, Stephen Warren wrote:
> On 01/14/2016 12:11 PM, Tom Rini wrote:
> >On Thu, Jan 14, 2016 at 11:35:39AM -0700, Stephen Warren wrote:
> >>On 01/14/2016 06:20 AM, Tom Rini wrote:
> >>>On Wed, Nov 25, 2015 at 05:56:33PM +0100, Albert ARIBAUD wrote:
> >>>
> >>>>As of gcc 5.2.1 for Thumb-1, it is not possible any
> >>>>more to assign gd from C code, as gd is mapped to r9,
> >>>>and r9 may now be saved in the prolog sequence, and
> >>>>restored in the epilog sequence, of any C functions.
> >>>>
> >>>>Therefore arch_setup_gd(), which is supposed to set
> >>>>r9, may actually have no effect, causing U-Boot to
> >>>>use a bad address to access GD.
> >>>>
> >>>>Fix this by never calling arch_setup_gd() for ARM,
> >>>>and instead setting r9 in arch/arm/lib/crt0.S, to
> >>>>the value returned by board_init_f_alloc_reserve().
> >>>>
> >>>>Signed-off-by: Albert ARIBAUD <albert.u.boot at aribaud.net>
> >>>>Reviewed-by: Simon Glass <sjg at chromium.org>
> >>>
> >>>Applied to u-boot/master, thanks!
> >>
> >>FYI, this commit causes U-Boot to fail (crash or hang during very
> >>early startup with zero UART output) on at least an NVIDIA Jetson
> >>TX1 (p2371-2180) board. Reverting just this in u-boot/master solves
> >>the issue. I have not tested other boards or looked at the code
> >>itself yet.
> >
> >Is that one of the systems where we have an ARM9 and then a Cortex-A?
> >FWIW, my pandaboard is up in Fedora currently.  I'm trying to do some
> >boot testing on what I have more often and then a bigger round of
> >unboxing and testing at -rc1/release time.
> 
> This board is AArch64. There's no SPL or dual-architecture U-Boot on
> this system; a boot CPU runs the boot ROM and and NVIDIA binary
> bootloader which loads U-Boot from disk and sets up the main CPU,
> then the main ARM CPU essentially jumps straight into the main
> U-Boot binary.

Oh, it's one of the aarch64 ones, OK.  Yeah, I need to get some for that
architecture in my setup.  It's annoyingly complex to get hikey flashed
but I can get my hands on a dragonboard soon, so once that's in I'll be
using that.

-- 
Tom
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