Re: [PATCH v2] powerpc/64: BE option to use ELFv2 ABI for big endian kernels

[Segher Boessenkool <segher@kernel.crashing.org>]

Hi!

On Tue, Apr 28, 2020 at 09:25:17PM +1000, Nicholas Piggin wrote:
> +config BUILD_BIG_ENDIAN_ELF_V2
> +	bool "Build big-endian kernel using ELFv2 ABI (EXPERIMENTAL)"
> +	depends on PPC64 && CPU_BIG_ENDIAN && EXPERT
> +	default n
> +	select BUILD_ELF_V2
> +	help
> +	  This builds the kernel image using the ELFv2 ABI, which has a
> +	  reduced stack overhead and faster function calls. This does not
> +	  affect the userspace ABIs.
> +
> +	  ELFv2 is the standard ABI for little-endian, but for big-endian
> +	  this is an experimental option that is less tested (kernel and
> +	  toolchain). This requires gcc 4.9 or newer and binutils 2.24 or
> +	  newer.

Is it clear that this is only for 64-bit?  Maybe this text should fit
that in somewhere?

It's not obvious to people who do not already know that ELFv2 is just
the (nick-)name of a particular ABI, not a new kind of ELF (it is just
version 1 ELF in fact), and that ABI is for 64-bit Power only.


Segher