Index: src/backend/port/tas/solaris_sparc.s
===================================================================
RCS file: /cvsroot/pgsql/src/backend/port/tas/solaris_sparc.s,v
retrieving revision 1.6
diff -c -c -r1.6 solaris_sparc.s
*** src/backend/port/tas/solaris_sparc.s	17 May 2006 22:06:19 -0000	1.6
--- src/backend/port/tas/solaris_sparc.s	17 May 2006 23:42:40 -0000
***************
*** 16,21 ****
--- 16,38 ----
  	.global pg_atomic_cas
  pg_atomic_cas:
  	
+ 	! "cas" only works on sparcv9 chips, and requies a compiler
+ 	! that is targeting sparcv9.  It will fail on a compiler
+ 	! targeting sparcv8, and of course will not be understood
+ 	! by a sparcv8 CPU.  If this fails on existing Solaris
+ 	! systems, we need to use a !defined(__sparcv9) test
+ 	! to fall back to the old "ldstub" call for sparcv8 compiles.
+ 	! gcc continues to use "ldstub" because there is no indication
+ 	! which sparc version it is targeting.
+ 	!
+ 	! There actually is a trick for embedding "cas" for a compiler
+ 	! that is targeting sparcv8:
+ 	!
+ 	!   http://cvs.opensolaris.org/source/xref/on/usr/src/lib/libc/sparc/threads/sparc.il
+ 	!
+ 	! This might work for sparc8:
+ 	! ldstub [%o0],%o1	! moves only a byte
+ 
  	cas     [%o0],%o2,%o1
  	mov     %o1,%o0
  	retl
Index: src/include/storage/s_lock.h
===================================================================
RCS file: /cvsroot/pgsql/src/include/storage/s_lock.h,v
retrieving revision 1.152
diff -c -c -r1.152 s_lock.h
*** src/include/storage/s_lock.h	29 Apr 2006 11:55:19 -0000	1.152
--- src/include/storage/s_lock.h	17 May 2006 23:43:03 -0000
***************
*** 311,316 ****
--- 311,320 ----
  {
  	register slock_t _res;
  
+ 	/*
+ 	 *	See comment in /pg/backend/port/tas/solaris_sparc.s for why this
+ 	 *	uses "ldstub", and that file uses "cas".
+ 	 */
  	__asm__ __volatile__(
  		"	ldstub	[%2], %0	\n"
  :		"=r"(_res), "+m"(*lock)