Do not adjust to the pagesize at runtime. Besides for the one-time

initialization overhead, there's a problem in that we never call
imalloc() and thus malloc_init() for zero-sized allocations. As a
result, malloc(0) returns NULL when it's the first or only malloc in
the program. Any non-zero allocation will initialize the malloc code
with the side-effect that subsequent zero-sized allocations return a
non-NULL pointer. This is because the pointer we return for zero-
sized allocations is calculated from malloc_pageshift, which needs
to be initialized at runtime on ia64.

The result of the inconsistent behaviour described above is that
configure scripts failed the test for a GNU compatible malloc. This
resulted in a lot of broken ports.

Other, even simpler, solutions were possible as well:
1.  initialize malloc_pageshift with some non-zero value (say 13 for
    8KB pages) and keep the runtime adjustment.
2.  Stop using malloc_pageshift to calculate ZEROSIZEPTR.

Removal of the runtime adjustment was chosen because then ia64 is the
same as any other platform. It is not to say that using a page size
obtained at runtime is bad per se. It's that there's currently a high
level of gratuity for its existence and the moment it causes problems
is the moment you need to get rid of it. Hence, it's not unthinkable
that this commit is (partially) reverted some time in the future when
we do have a good reason for it and a good way to achieve it.

Approved by: re@ (rwatson)
Reported by: kris (portmgr@) -- may the ports be with you

lib/libc/stdlib/malloc.c

@@ -50,9 +50,8 @@ __FBSDID("$FreeBSD$");
 #       define malloc_minsize		16U
 #   endif
 #   if defined(__ia64__)
-	static int malloc_pageshift_value;
-#	define malloc_pageshift		malloc_pageshift_value
-#       define malloc_minsize		16U
+#	define malloc_pageshift		13U
+#	define malloc_minsize		16U
 #   endif
 #   if defined(__alpha__)
 #       define malloc_pageshift		13U
@@ -414,11 +413,6 @@ malloc_init(void)
     int i, j;
     int save_errno = errno;
 
-#ifdef __ia64__
-    malloc_pageshift = 0;
-    while ((1L << malloc_pageshift) < getpagesize())
-	    malloc_pageshift++;
-#endif
     INIT_MMAP();
 
 #ifdef MALLOC_EXTRA_SANITY