wernermisc/m1/patches/rtems/lm32-stack-alignment.patch

This patch is under review:
https://www.rtems.org/bugzilla/show_bug.cgi?id=1956

The comments in cpukit/score/cpu/lm32/rtems/score/cpu.h state that
CPU_STACK_ALIGNMENT should either be 0 or >= CPU_ALIGNMENT. The
latter was 8, the former is 4.

Further investigation revealed that, contrary to what the comment
says, 0 is not a valid value for CPU_STACK_ALIGNMENT.

This patch sets CPU_ALIGNMENT to 4, since we don't have any machine
word larger than that. (doubles and long longs are handled by
software and either extremely slow already or rare.)

The patch also corrects the misleading comment before
CPU_STACK_ALIGNMENT.

I'm not sure if this fix has any real-life impact on M1 behaviour,
but I guess it can't hurt.

- Werner

Index: rtems/cpukit/score/cpu/lm32/rtems/score/cpu.h
===================================================================
--- rtems.orig/cpukit/score/cpu/lm32/rtems/score/cpu.h	2011-11-12 03:01:35.000000000 -0300
+++ rtems/cpukit/score/cpu/lm32/rtems/score/cpu.h	2011-11-12 03:03:46.000000000 -0300
@@ -637,7 +637,7 @@
  *
  *  XXX document implementation including references if appropriate
  */
-#define CPU_ALIGNMENT              8
+#define CPU_ALIGNMENT              4
 
 /**
  *  This number corresponds to the byte alignment requirement for the
@@ -687,9 +687,10 @@
  *  stack.  This alignment requirement may be stricter than that for the
  *  data types alignment specified by @ref CPU_ALIGNMENT.  If the
  *  @ref CPU_ALIGNMENT is strict enough for the stack, then this should be
- *  set to 0.
+ *  set to @ref CPU_ALIGNMENT.
  *
- *  @note This must be a power of 2 either 0 or greater than @ref CPU_ALIGNMENT.
+ *  @note This must be a power of 2 either equal to or greater than
+ *  @ref CPU_ALIGNMENT.
  *
  *  Port Specific Information:
  *