[PATCH] ARM: decompressor: clear SCTLR.A bit for v7 cores

On Thursday 25 October 2012, Rob Herring wrote:

quoted

On Thu, Oct 11, 2012 at 07:43:22AM -0500, Rob Herring wrote:

quoted

With recent compilers and move to generic unaligned.h in commit d25c881
(ARM: 7493/1: use generic unaligned.h), unaligned accesses will be used
by the LZO decompressor on v7 cores. So we need to make sure unaligned
accesses are allowed by clearing the SCTLR A bit.

I just read this in http://gcc.gnu.org/gcc-4.7/changes.html:

  On ARM, when compiling for ARMv6 (but not ARMv6-M), ARMv7-A, ARMv7-R, or
  ARMv7-M, the new option -munaligned-access is active by default, which for
  some source codes generates code that accesses memory on unaligned addresses.
  This will require the kernel of those systems to enable such accesses
  (controlled by CP15 register c1, refer to ARM documentation). Alternatively
  or for compatibility with kernels where unaligned accesses are not supported,
  all code has to be compiled with -mno-unaligned-access. Linux/ARM in official
  releases has automatically and unconditionally supported unaligned accesses
  as emitted by GCC due to this option being active, since Linux version 2.6.28.

I don't think there is such a thing as ARMv6-M.

There is, that would be the Cortex-M0/M0+/M1. You cannot run Linux on these.

	Arnd