[U-Boot] Latest u-boot release on BeagleBone Black for FreeBSD

[Jeroen Hofstee]

Hello Xuebing, (freebsd-arm added on cc),

On di, 2014-04-08 at 16:52 +0800, Xuebing Wang wrote:
> Hi u-boot community,
> 
> I am trying to port u-boot (release u-boot-2014.04-rc3.tar.bz2) to 
> FreeBSD on BeagleBone Black.
> 
> In FreeBSD, there is a u-boot loader (named ubldr), which can call 
> u-boot API to get fdt (Flat Device Tree) data.
> 
> I have to comment out below 3 lines, in order to get correct fdt data in 
> FreeBSD ubldr from u-boot. Would you please advice what is the best way 
> to fix this?
> 
> In file common/env_common.c:
> const uchar *env_get_addr(int index)
> {
> //      if (gd->env_valid)
> //              return (uchar *)(gd->env_addr + index);
> //      else
>                  return &default_environment[index];
> }
> 

Assuming that you checked that your environment is valid you might be
facing the fact that the gd pointer is corrupted. gd is a pointer to the
"global data" and used for storing globals which are available before
and after relocation. On (32bit) ARM this value used to be stored in
register r8 but moved to r9 (llvm cannot reserve an arbitrary register,
but can reserve r9 for platform specific usage). If ubldr uses r9 you
end up with a invalid gd pointer when calling back into u-boot. ubldr
now reserves r8 and r9 so a recent version should work fine on an older
U-boot as well as current master.

Can you check the latest ubldr?

Regards,
Jeroen