1 files changed, 47 insertions, 0 deletions
diff --git a/byterun/unix.c b/byterun/unix.c
index d1e29ec39..465b68409 100644
--- a/byterun/unix.c
+++ b/byterun/unix.c
@@ -207,3 +207,50 @@ char * caml_dlerror(void)
 
 #endif
 
+#ifdef USE_MMAP_INSTEAD_OF_MALLOC
+
+/* The code below supports the use of mmap() rather than malloc()
+   for allocating the chunks composing the major heap.
+   This code is needed for the IA64 under Linux, where the native
+   malloc() implementation can return pointers several *exabytes* apart,
+   (some coming from mmap(), other from sbrk()); this makes the
+   page table *way* too large.
+   No other tested platform requires this hack so far.  However, it could
+   be useful for other 64-bit platforms in the future. */
+
+#include <sys/mman.h>
+
+char *aligned_mmap (asize_t size, int modulo, void **block)
+{
+  char *raw_mem;
+  unsigned long aligned_mem;
+  Assert (modulo < Page_size);
+  raw_mem = (char *) mmap(NULL, size + Page_size, PROT_READ | PROT_WRITE,
+                          MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  if (raw_mem == MAP_FAILED) return NULL;
+  *block = raw_mem;
+  raw_mem += modulo;                /* Address to be aligned */
+  aligned_mem = (((unsigned long) raw_mem / Page_size + 1) * Page_size);
+#ifdef DEBUG
+  {
+    unsigned long *p;
+    unsigned long *p0 = (void *) *block,
+                  *p1 = (void *) (aligned_mem - modulo),
+                  *p2 = (void *) (aligned_mem - modulo + size),
+                  *p3 = (void *) ((char *) *block + size + Page_size);
+
+    for (p = p0; p < p1; p++) *p = Debug_filler_align;
+    for (p = p1; p < p2; p++) *p = Debug_uninit_align;
+    for (p = p2; p < p3; p++) *p = Debug_filler_align;
+  }
+#endif
+  return (char *) (aligned_mem - modulo);
+}
+
+void aligned_munmap (char * addr, asize_t size)
+{
+  int retcode = munmap (addr, size + Page_size);
+  Assert(retcode == 0);
+}
+
+#endif