[U-Boot] [PATCH v2] 85xx: Ensure BSS segment isn't linked at address 0

[Peter Tyser]

When U-Boot is relocated from flash to RAM pointers are modified
accordingly.  However, pointers initialzed with NULL values should not
be modified so that they maintain their intended NULL value.  If the
BSS segment is linked at address 0 its address will not be
updated as necessary during relocation.

This is a temporary workaround.  The end goal is to add support to
U-Boot to dynamically locate the BSS at an arbitrary address at
runtime.  When the ability to fixup the BSS inteligently is
added, this workaround can be removed and the 85xx link script
can put the BSS at a fixed address at link time.

Signed-off-by: Peter Tyser <ptyser at xes-inc.com>
---
Changes since v1:
- Updated commit title and description
- Cleaned up logic to determine if we need to fixup bss address

 cpu/mpc85xx/u-boot.lds |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/cpu/mpc85xx/u-boot.lds b/cpu/mpc85xx/u-boot.lds
index a347cd1..183dce9 100644
--- a/cpu/mpc85xx/u-boot.lds
+++ b/cpu/mpc85xx/u-boot.lds
@@ -131,6 +131,17 @@ SECTIONS
 
   . = RESET_VECTOR_ADDRESS + 0x4;
 
+  /*
+   * Make sure that the bss segment isn't linked at 0x0, otherwise its
+   * address won't be updated during relocation fixups.  Note that
+   * this is a temporary fix.  Code to dynamically the fixup the bss
+   * location will be added in the future.  When the bss relocation
+   * fixup code is present this workaround should be removed.
+   */
+#if (RESET_VECTOR_ADDRESS == 0xfffffffc)
+  . |= 0x10;
+#endif
+
   __bss_start = .;
   .bss (NOLOAD)       :
   {
-- 
1.6.2.1