From: Philippe Waroquiers <philippe.waroquiers@skynet.be>
Date: Wed, 13 Mar 2013 22:03:31 +0000 (+0000)
Subject: Document that user level client stack switches might cause crashes
X-Git-Tag: svn/VALGRIND_3_9_0~354
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=52b0e470c340f82fdfa8ef813ace90c75d8e62b0;p=thirdparty%2Fvalgrind.git

Document that user level client stack switches might cause crashes
and that these crahses might be avoided using VALGRIND_STACK_REGISTER
See bug 316613


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13327
---

diff --git a/docs/xml/manual-core-adv.xml b/docs/xml/manual-core-adv.xml
index 00376a1d5b..73bdb5a46b 100644
--- a/docs/xml/manual-core-adv.xml
+++ b/docs/xml/manual-core-adv.xml
@@ -247,11 +247,12 @@ tool-specific macros).</para>
     between start and end is a unique stack.  Returns a stack identifier
     that can be used with other
     <computeroutput>VALGRIND_STACK_*</computeroutput> calls.</para>
-    <para>Valgrind will use this information to determine if a change to
-    the stack pointer is an item pushed onto the stack or a change over
-    to a new stack.  Use this if you're using a user-level thread package
-    and are noticing spurious errors from Valgrind about uninitialized
-    memory reads.</para>
+    <para>Valgrind will use this information to determine if a change
+    to the stack pointer is an item pushed onto the stack or a change
+    over to a new stack.  Use this if you're using a user-level thread
+    package and are noticing crashes in stack trace recording or
+    spurious errors from Valgrind about uninitialized memory
+    reads.</para>
 
     <para><command>Warning:</command> Unfortunately, this client request is
     unreliable and best avoided.</para>
diff --git a/docs/xml/manual-core.xml b/docs/xml/manual-core.xml
index a60c3a43a6..e489fd6f05 100644
--- a/docs/xml/manual-core.xml
+++ b/docs/xml/manual-core.xml
@@ -2609,13 +2609,16 @@ shipped.</para>
     <para><computeroutput>Warning: client switching stacks?</computeroutput></para>
 
     <para>Valgrind spotted such a large change in the stack pointer
-    that it guesses the client is switching to
-    a different stack.  At this point it makes a kludgey guess where the
-    base of the new stack is, and sets memory permissions accordingly.
-    You may get many bogus error messages following this, if Valgrind
-    guesses wrong.  At the moment "large change" is defined as a change
-    of more that 2000000 in the value of the
-    stack pointer register.</para>
+    that it guesses the client is switching to a different stack.  At
+    this point it makes a kludgey guess where the base of the new
+    stack is, and sets memory permissions accordingly.  At the moment
+    "large change" is defined as a change of more that 2000000 in the
+    value of the stack pointer register.  If Valgrind guesses wrong,
+    you may get many bogus error messages following this and/or have
+    crashes in the stack trace recording code.  You might avoid these
+    problems by informing Valgrind about the stack bounds using
+    VALGRIND_STACK_REGISTER client request. </para>
+
   </listitem>
 
   <listitem>