Changeset 27297 in vbox

Timestamp:

Mar 11, 2010 5:48:40 PM (15 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

58704

Message:

alloc-ef.cpp: RTALLOC_EFENCE_ALIGNMENT.

Location:

trunk/src/VBox/Runtime/r3

Files:

• alloc-ef.cpp (modified) (1 diff)
• alloc-ef.h (modified) (3 diffs)

trunk/src/VBox/Runtime/r3/alloc-ef.cpp

@@ -292 +292 @@
 #endif
     }
-
-    /** @todo this alignment decreases fence accuracy, but there are lots
-     * of places in VirtualBox which assumes that the allocation is aligned
-     * properly even for totally unusual allocation sizes, otherwise assertions
-     * are triggered, which ensure a particular alignment of elements. */
-    cb = RT_ALIGN_Z(cb, ARCH_BITS / 8);
+    cb = RT_ALIGN_Z(cb, RTALLOC_EFENCE_ALIGNMENT);
 
 #ifdef RTALLOC_EFENCE_TRACE

trunk/src/VBox/Runtime/r3/alloc-ef.h

@@ -54 +54 @@
 #define RTALLOC_EFENCE_SIZE             PAGE_SIZE
 
+/** @def RTALLOC_EFENCE_ALIGNMENT
+ * The allocation alignment, power of two of course.
+ *
+ * Normally, 1 would be the perfect choice here, except that there is code, like
+ * the atomic operations in iprt/asm.h, that makes assumptions about naturally
+ * aligned data members.  If the code you're working against doesn't have strict
+ * alignment requirements, changing this to 1 is highly desirable.
+ */
+#if 1
+# define RTALLOC_EFENCE_ALIGNMENT       (ARCH_BITS / 8)
+#else
+# define RTALLOC_EFENCE_ALIGNMENT       1
+#endif
+
 /** @def RTALLOC_EFENCE_IN_FRONT
  * Define this to put the fence up in front of the block.
@@ -95 +109 @@
  * unprotected but not allocated area of memory, the so called no man's land.
  */
-#define RTALLOC_EFENCE_NOMAN_FILLER           0xaa
+#define RTALLOC_EFENCE_NOMAN_FILLER     0xaa
 
 /** @def RTALLOC_EFENCE_FENCE_FILLER
@@ -101 +115 @@
  * fence itself, as debuggers can usually read them.
  */
-#define RTALLOC_EFENCE_FENCE_FILLER           0xcc
+#define RTALLOC_EFENCE_FENCE_FILLER     0xcc
 
 #if defined(DOXYGEN_RUNNING)