[U-Boot] [PATCH 01/10] Move board_init_f_mem() into a common location

[Jeroen Hofstee <jeroen@myspectrum.nl>]

Hello Simon,

On 16-04-15 03:14, Simon Glass wrote:
> +
> +DECLARE_GLOBAL_DATA_PTR;
> +
> +ulong board_init_f_mem(ulong top)
> +{
> +	/* TODO(sjg at chromium.org): Figure out how x86 can use this */
> +#ifndef CONFIG_X86
> +	/* Leave space for the stack we are running with now */
> +	top -= 0x40;
> +
> +	top -= sizeof(struct global_data);
> +	top = ALIGN(top, 16);
> +	gd = (struct global_data *)top;
> +	memset((void *)gd, '\0', sizeof(*gd));
> +

Above piece of code is on my TODO list as well. Like x86, clang cannot
directly assign gd. What I still need to check is why this reassignment is
needed in the first place. Typically, at least for ARM, allocating an 
initial
gd in _main and copying it over in relocate suffices for common boards.

This doesn't work if there is a valid use case for needing gd before calling
main, but I am not aware of any (but haven't found time to google for any
as well, so it doesn't mean there isn't any).

That said, if there is valid reason to reassign gd, clang could do that 
if there
was a macro e.g. set_gd(new_gd) instead of a direct assignment. Since 
this is a
cross arch patchset, that might be something to consider (and likely 
solves the
"Figure out how x86 can use this" as well).

Regards,
Jeroen