Segfault during `make bootstrap' under certain recent versions of the

Linux kernel.

Copied from the trunk PROBLEMS file, with the following part removed,
because I am not sure whether it is true for 21.4:

Configure can overcome the problem of exec-shield if the architecture is
x86 and the program setarch is present.  On other architectures no
workaround is known.

diff --git a/etc/ChangeLog b/etc/ChangeLog
index 17fd31b51c6d683917aa394aa399b9047381cdc7..c5233d118154ce2589ea095ba00e065b3ac35527 100644 (file)
--- a/etc/ChangeLog
+++ b/etc/ChangeLog
@@ -1,3 +1,8 @@
+2005-02-17  Francesco Potort\e,Al\e(B  <pot@gnu.org>
+
+       * PROBLEMS: Document exec-shield Linux problem.  Do not mention
+       that configure can overcome it on i386: not sure for 21.4.
+
 2003-05-28  Dave Love  <fx@gnu.org>
 
        * ORDERS.EUROPE, ORDERS.JAPAN: Removed.

diff --git a/etc/PROBLEMS b/etc/PROBLEMS
index 6f07e886ed7022665c39e1e82abb3477c28dacf5..f09dc2c6cb9dd48336a89276ee1b0730d7632b67 100644 (file)
--- a/etc/PROBLEMS
+++ b/etc/PROBLEMS
@@ -136,6 +136,33 @@ in the `/gnu/emacs/windows' directory a program called `djtarnt.exe'
 which can be used to unpack `.tar.gz' and `.zip' archives without
 mangling them.
 
+* Segfault during `make bootstrap' under certain recent versions of the Linux kernel.
+
+With certain recent Linux kernels (like the one of Redhat Fedora Core
+1 and 2), the new "Exec-shield" functionality is enabled by default, which
+creates a different memory layout that breaks the emacs dumper.
+
+You can check the Exec-shield state like this:
+
+    cat /proc/sys/kernel/exec-shield
+
+It returns non-zero when Exec-shield is enabled, 0 otherwise.  Please
+read your system documentation for more details on Exec-shield and
+associated commands.  Exec-shield can be turned off with this command:
+
+    echo "0" > /proc/sys/kernel/exec-shield
+
+When Exec-shield is enabled, building Emacs will segfault during the
+execution of this command:
+
+    ./temacs --batch --load loadup [dump|bootstrap]
+
+To work around this problem, it is necessary to temporarily disable
+Exec-shield while building Emacs, or, on x86, by using the `setarch'
+command when running temacs like this:
+
+    setarch i386 ./temacs --batch --load loadup [dump|bootstrap]
+
 * Emacs crashes when dumping itself on Mac PPC running Yellow Dog GNU/Linux.
 
 The crashes happen inside the function Fmake_symbol; here's a typical