Technical Informations - Novell SP2 - RELEASE NOTES Release Note

Chapter 11. Technical Informations
This section contains a number of technical changes and enhancements for the experienced user.
• Locale Settings in ~/.i18n
If you are not satisfied with locale system defaults, change the settings in ~/.i18n. Entries in ~/
.i18n override system defaults from /etc/sysconfig/language. Use the same variable names
but without the RC_ namespace prefixes, for example, use LANG instead of RC_LANG. For information
about locales in general, see "Language and Country-Specific Settings" in the Reference Manual.
• Configuration of kdump
The kernel is crashing or otherwise misbehaving and a kernel core dump needs to be captured for
analysis.
A description on how to setup kdump can be found under the following URL: http://www.novell.com/
support/search.do?cmd=displayKC&docType=kc&externalId=3374462&sliceId=SAL_Public
• Realtime Applications
When running real-time applications on larger systems, lower maximum latencies can be achieved by
employing the new disable_buffer_lru kernel command-line option. This disables the per-CPU
LRU in the buffer cache, and may thus decrease overall filesystem performance.
• JPackage Standard for Java Packages
Java packages are changed to follow the JPackage Standard (http://www.jpackage.org/). Read the
documentation in /usr/share/doc/packages/jpackage-utils/ for information.
• Loading unsupported kernel drivers
To load unsupported kernel drivers automatically during boot, set the sysconfig variable
LOAD_UNSUPPORTED_MODULES_AUTOMATICALLY
config to "yes".
• Nonexecutable Stack
Already introduced for SUSE Linux Enterprise Server 9 on the x86-64 (AMD64) architecture with
64-bit kernels, the Linux kernel in SUSE Linux Enterprise Server also supports nonexecutable stack
(NX) on x86 for CPUs that support it (Intel Prescott and AMD64) with 32-bit kernels. For this to work,
the kernel with PAE support, kernel-bigsmp, must be installed. Go into YaST and install that kernel
instead of your default kernel. For 64-bit kernels, all kernels support NX.
The nonexecutable stack improves the security of your system. Many security vulnerabilities are stack
overflows, where an attacker overwrites the stack of your program by feeding oversized data to the
application that fails to properly check the length. Depending on the details of the program, with
nonexecutable stack, these vulnerabilities may either not be exploitable (and only crash the program,
resulting in a DoS) or at least be significantly harder to exploit.
Some applications do require executable stacks. The compiler detects this during compilation and marks
the binaries accordingly. The kernel enable an executable stack for them to allow them to work.
On x86-64, to provide a higher level of security, the user can pass noexec=on on the kernel command
line. The kernel then uses a nonexecutable stack unconditionally and also marks the data section of a
in
/etc/sysconfig/hardware/
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