[U-Boot] P2041RDB: gcc 4.8.2/binutils 2.23.1 default to new GOT table layout

[U-Boot] P2041RDB: gcc 4.8.2/binutils 2.23.1 default to new GOT table layout

[Joerg Albert]

Hi,

I've recently compiled U-Boot (fsl-sdk-v1.3.2) for P2041RDB and had a
problem with ARP requests flooding if the peer was not there.
It turned out that NetArpWaitTimerStart was not relocated to RAM, but
remained in flash, so it couldn't be updated.

Looking at the global offset table, it looks like the linker generates (by
default) a new layout, without _GLOBAL_OFFSET_TABLE_ [-1] == blrl (as
required by the EABI) and NetArpWaitTimerStart is the entry at
_GLOBAL_OFFSET_TABLE_ [-1].
u-boot.lds still assumes the blrl in the GOT.

Putting a

LDFLAGS_FINAL += --bss-plt

into board/freescale/p2041rdb/config.mk

brought the blrl instruction in the GOT back and solved the ARP problem.

I compiled v2014.01-116-g0c57033 for P2041RDB without --bss-plt and the blrl
was missing in the GOT as well.

--bss-plt is rarely documented, will it cause some other problems?

Are gcc 4.8.x and binutils 2.23.1 recommended to use with U-Boot or shall we
stick to older versions?

Regards,
Joerg

[U-Boot] P2041RDB: gcc 4.8.2/binutils 2.23.1 default to new GOT table layout

[Scott Wood]

On Mon, 2014-02-10 at 15:19 +0000, Joerg Albert wrote:
> Hi,
> 
> I've recently compiled U-Boot (fsl-sdk-v1.3.2) for P2041RDB and had a
> problem with ARP requests flooding if the peer was not there.
> It turned out that NetArpWaitTimerStart was not relocated to RAM, but
> remained in flash, so it couldn't be updated.
> 
> Looking at the global offset table, it looks like the linker generates (by
> default) a new layout, without _GLOBAL_OFFSET_TABLE_ [-1] == blrl (as
> required by the EABI) and NetArpWaitTimerStart is the entry at
> _GLOBAL_OFFSET_TABLE_ [-1].
> u-boot.lds still assumes the blrl in the GOT.
> 
> Putting a
> 
> LDFLAGS_FINAL += --bss-plt

Do you mean -mbss-plt?

> into board/freescale/p2041rdb/config.mk
> 
> brought the blrl instruction in the GOT back and solved the ARP problem.
> 
> I compiled v2014.01-116-g0c57033 for P2041RDB without --bss-plt and the blrl
> was missing in the GOT as well.
> 
> --bss-plt is rarely documented, will it cause some other problems?
> 
> Are gcc 4.8.x and binutils 2.23.1 recommended to use with U-Boot or shall we
> stick to older versions?

For the SDK U-Boot, it's best to use the toolchain that came with the
SDK.

For mainline U-Boot, please submit a patch.

-Scott