[U-Boot] [RFC] RFC: convert MPC8536DS to use generic board

[Scott Wood]

On Sat, 2014-04-26 at 09:36 -0700, York Sun wrote:
> On 04/26/2014 02:22 AM, Wolfgang Denk wrote:
> >> +#ifdef CONFIG_PPC
> >> +	gd = (gd_t *) (CONFIG_SYS_INIT_RAM_ADDR + CONFIG_SYS_GBL_DATA_OFFSET);
> >> +	__asm__ __volatile__("":::"memory");
> >> +#endif
> > 
> > Again, this is a global change.  Why is this now needed?
> > 
> 
> It has been this way for powerpc. Do we have an alternative?

gd is already initialized at the beginning of board_init_f().  If PPC
needs gd before board_init_f(), then add PPC (or some other relevant
symbol if it's not all PPC) to the #ifndef X86.  In any case, there
should be no need to add yet another initialization of gd.
cpu_init_early_f() already initialized and cleared it.  Also, if gd
really is needed before board_init_f(), then we probably need to skip
clearing gd in board_init_f().

As for the memory clobber, if nobody can come up with a reason for its
existence, then just let it go away.  At the very least, don't copy the
barrier without also copying the comment that went with it -- but I'm
really not seeing what it's trying to order.  gd is a register, not
memory.  Maybe some versions of GCC had a bug that the clobber worked
around -- does it apply to any recent GCC?  In any case, for mpc85xx, gd
was previously initalized as discussed above.

-Scott