Re: [PATCH v2 05/13] powerpc: use linux/unaligned/le_struct.h on LE power7

On Fri, May 14, 2021 at 1:48 PM Segher Boessenkool
[off-list ref] wrote:

On Fri, May 14, 2021 at 12:00:53PM +0200, Arnd Bergmann wrote:

quoted

Little-endian POWER7 kernels disable
CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS because that is not supported on
the hardware, but the kernel still uses direct load/store for explicti
get_unaligned()/put_unaligned().

I assume this is a mistake that leads to power7 having to trap and fix
up all these unaligned accesses at a noticeable performance cost.

The fix is completely trivial, just remove the file and use the
generic version that gets it right.

LE p7 isn't supported (it requires special firmware), and no one uses it
anymore, also not for development.  It was used for powerpc64le-linux
development before p8 was widely available.

Ok, thanks for the clarification.

Should we just remove the Kconfig option for it then as further cleanup?
Is there any other code such as alignment trap handling that could be
removed if LE POWER7 gets dropped?

      Arnd