[U-Boot] [PATCH] arm: lds: Remove libgcc eabi exception handling tables

[Albert ARIBAUD <albert.u.boot@aribaud.net>]

Hi Michal,

On Thu, 25 Jul 2013 16:16:46 +0200, Michal Simek
<michal.simek@xilinx.com> wrote:

> Remove ARM eabi exception handling tables (for frame unwinding).
> AFAICT, u-boot stubs away the frame unwiding routines, so the tables will
> more or less just consume space. It should be OK to remove them.
> 
> Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
> Signed-off-by: Michal Simek <michal.simek@xilinx.com>
> ---
> This patch was sent to ML as RFC (May 9)
> 
> Here is the origin response in connection to this patch.
> 
> Ok, so Michal and I just did some fiddling with zynq builds and
> *exidx* sections.
> 
> By default the *exidx* sections are between rodata and data, so
> removing them causes many apparent changes at the binary level.
> However, builds of zynq based on ARM master with the patch above vs
> master with a patch mapping *exidx* sections after BSS gives identical
> binaries. Thus the RFC has no functional effect.
> 
> Also, ARM EHABI states that [exception] Tables are not required for ABI
> compliance at the C/Assembler level but are required for C++.
> 
> http://infocenter.arm.com/help/topic/com.arm.doc.ihi0038a/IHI0038A_ehabi.pdf
> 
> So as long as we don't put any C++ code in U-Boot (a prospect that I
> don't see happening any time soon), this RFC is safe and either is a
> no-op or removes useless bytes from the binary.
> 
> ---
>  arch/arm/cpu/u-boot.lds | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/arm/cpu/u-boot.lds b/arch/arm/cpu/u-boot.lds
> index 3037885..8894c8a 100644
> --- a/arch/arm/cpu/u-boot.lds
> +++ b/arch/arm/cpu/u-boot.lds
> @@ -113,4 +113,6 @@ SECTIONS
>  	/DISCARD/ : { *(.plt*) }
>  	/DISCARD/ : { *(.interp*) }
>  	/DISCARD/ : { *(.gnu*) }
> +	/DISCARD/ : { *(.ARM.exidx*) }
> +	/DISCARD/ : { *(.gnu.linkonce.armexidx.*) }
>  }
> --
> 1.8.2.3
> 

Applied to u-boot-arm/master, thanks!

Amicalement,
-- 
Albert.