From: Julian Seward <jseward@acm.org>
Date: Sat, 15 Oct 2005 00:41:50 +0000 (+0000)
Subject: Add comments re loss of pointercheck.
X-Git-Tag: svn/VALGRIND_3_1_0~307
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=100db4b3eb490db047a107310884795da9883358;p=thirdparty%2Fvalgrind.git

Add comments re loss of pointercheck.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@4925
---

diff --git a/coregrind/m_aspacemgr/aspacemgr.c b/coregrind/m_aspacemgr/aspacemgr.c
index 3a27aa78bd..5ca36e4738 100644
--- a/coregrind/m_aspacemgr/aspacemgr.c
+++ b/coregrind/m_aspacemgr/aspacemgr.c
@@ -253,6 +253,16 @@
   complains if there is a difference.  --sanity-level=3 runs it before
   and after each syscall, which is a powerful, if slow way of finding
   buggy syscall wrappers.
+
+  Loss of pointercheck
+  ~~~~~~~~~~~~~~~~~~~~
+  Up to and including Valgrind 2.4.1, x86 segmentation was used to
+  enforce seperation of V and C, so that wild writes by C could not
+  trash V.  This got called "pointercheck".  Unfortunately, the new
+  more flexible memory layout, plus the need to be portable across
+  different architectures, means doing this in hardware is no longer
+  viable, and doing it in software is expensive.  So at the moment we
+  don't do it at all.
 */