Changeset 36372 in vbox for trunk/src/VBox

Timestamp:

Mar 23, 2011 4:35:01 PM (14 years ago)

Author:

vboxsync

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

70719

Message:

RTR0MemObjSize: Correct documentation and added alignment guarantee.

File:

• trunk/src/VBox/Runtime/r0drv/memobj-r0drv.cpp (modified) (3 diffs)

trunk/src/VBox/Runtime/r0drv/memobj-r0drv.cpp

@@ -64 +64 @@
     Assert(cbSelf >= sizeof(*pNew));
     Assert(cbSelf == (uint32_t)cbSelf);
+    AssertMsg(RT_ALIGN_Z(cb, PAGE_SIZE) == cb, ("%#zx\n", pMem->cb));
 
     /*
@@ -226 +227 @@
  * Gets the size of a ring-0 memory object.
  *
- * @returns The address of the memory object.
+ * The returned value may differ from the one specified to the API creating the
+ * object because of alignment adjustments.  The minimal alignment currently
+ * employed by any API is PAGE_SIZE, so the result can safely be shifted by
+ * PAGE_SHIFT to calculate a page count.
+ *
+ * @returns The object size.
  * @returns 0 if the handle is invalid (asserts in strict builds) or if there isn't any mapping.
  * @param   MemObj  The ring-0 memory object handle.
@@ -241 +247 @@
     AssertMsgReturn(pMem->u32Magic == RTR0MEMOBJ_MAGIC, ("%p: %#x\n", pMem, pMem->u32Magic), 0);
     AssertMsgReturn(pMem->enmType > RTR0MEMOBJTYPE_INVALID && pMem->enmType < RTR0MEMOBJTYPE_END, ("%p: %d\n", pMem, pMem->enmType), 0);
+    AssertMsg(RT_ALIGN_Z(pMem->cb, PAGE_SIZE) == pMem->cb, ("%#zx\n", pMem->cb));
 
     /* return the size. */