[U-Boot] [PATCH v2] 85xx: Ensure BSS segment isn't linked at address 0
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@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) : {
Dear Peter Tyser,
In message 1254933900-16859-1-git-send-email-ptyser@xes-inc.com you wrote:
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@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(-)
Applied to "reloc" branch, thanks.
Best regards,
Wolfgang Denk
On Oct 7, 2009, at 5:34 PM, Wolfgang Denk wrote:
Dear Peter Tyser,
In message 1254933900-16859-1-git-send-email-ptyser@xes-inc.com you wrote:
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@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(-)
Applied to "reloc" branch, thanks.
Is the intent to merge "reloc" for v2009.11 or post?
- k
On Thursday 08 October 2009 04:47:57 Kumar Gala wrote:
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(-)
Applied to "reloc" branch, thanks.
Is the intent to merge "reloc" for v2009.11 or post?
AFAIK, this branch will be merged in this release. Bigger changes like the bss move to a fixed address and consolidation of the relocation code in C are postponed to the next release.
Cheers, Stefan
-- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-0 Fax: (+49)-8142-66989-80 Email: office@denx.de
Dear Kumar Gala,
In message ECB99FF0-6A99-4165-B5FA-F5B4CE143B71@kernel.crashing.org you wrote:
Applied to "reloc" branch, thanks.
Is the intent to merge "reloc" for v2009.11 or post?
Yes :-)
I will merge it by the end of this week, as previously announced.
Best regards,
Wolfgang Denk
participants (4)
-
Kumar Gala -
Peter Tyser -
Stefan Roese -
Wolfgang Denk