[U-Boot] mx25pdk does not boot with 3ff46cc42b9d7

[Bill Pringlemeir <bpringlemeir@nbsps.com>]

On  5 Jan 2015, festevam at gmail.com wrote:

> I noticed that mx25pdk (ARM926) does not boot anymore with top of tree
> U-boot.
>
> Doing a git bisect resulted in the following commit as being the
> guilty one:
>
> commit 3ff46cc42b9d73d01c86df904425704410958470
> Author: Georges Savoundararadj <savoundg@gmail.com>
> Date:   Tue Oct 28 23:16:11 2014 +0100
>
> arm: relocate the exception vectors
>
> This commit relocates the exception vectors.
> As ARM1176 and ARMv7 have the security extensions, it uses VBAR.  For
> the other ARM processors, it copies the relocated exception vectors to
> the correct address: 0x00000000 or 0xFFFF0000.
>
> Signed-off-by: Georges Savoundararadj <savoundg@gmail.com>
> Acked-by: Albert ARIBAUD <albert.u.boot@aribaud.net>
> Cc: Tom Warren <twarren@nvidia.com>
>
> Any ideas?

$ git show 3ff46cc42b9d73d01c86df9044257

/*
 * Default/weak exception vectors relocation routine
 *
 * This routine covers the standard ARM cases: normal (0x00000000),
 * high (0xffff0000) and VBAR. SoCs which do not comply with any of
 * the standard cases must provide their own, strong, version.
 */

The code looks correct.  However, the imx25 has the HAB and some default
vectors set up.  Do you assume they overwrite the HAB vectors?  For the
imx25, the 'V bit = 0' for the physical HAB ROM location, but it can be
remapped to 0xffff0000.  However, there is nothing there (0xffff0000)
initially and this only makes sense with the MMU enabled.

I am not sure what happened before; why it worked.  Maybe you could
define an empty relocate_vectors() in the imx25 board file and see if
everything is ok?  I don't think that a write to the ROM code will BUS
error?  If a write BUS errors, then the empty routine will work/boot.
However, u-boot will not be handling the vectors unless we hook in the
IRAM at 0x7801FFFF, where I guess the ROM code (at address zero)
branches too.

Fwiw,
Bill Pringlemeir.