LTC bulletin: July 16, 2001

News in brief from IBM's Linux Technology Center 

Maya Stodte (mstodte@us.ibm.com)
Contributing editor, developerWorks

July 2001

Our biweekly news in brief from the Linux Technology Center -- where all the Linux-related technologies happening inside IBM are tracked -- includes some new patches, among them Internationalization and Samba, and several new releases. The global spinlock list and usage document has been updated. JFS has released version 1.0. Distributed Lock Manager has released version 0.4, with some fairly major changes. And the prolific Richard Moore is publishing another white paper. To find out more about any of these projects, go directly to the Linux Technology Center.

EVMS
The Enterprise Volume Management System, which is now hosted on SourceForge, has released version 0.1.3. EVMS does logical volume management with plug-in model architecture in order to maximize extensibility and flexibility. Among the changes mentioned in the release notes are:

• Engine and Dlist code is now built with autoconf
• PluginID structure is changed, and kernel code is synced with Engine
• Task Structure is defined for UI interactions
• Support for SUN Solaris X86, UNIXWare, and BSD partitions is in the kernel code
• Feature Discovery is available in the Engine
• Engine API has been cleaned up
• DOS (default) Segment is available for the Engine
• Write support is enabled for Engine Plugins (beware!)
• Minor numbers stored in EVMS System Data are now honored at discovery time

Internationalization patches for GNU bash
The Internationalization patches for GNU bash have been updated. According to the changelog, the patch fixed a bug when run with the 'TERM' setting other than 'vt100'. The authors for the patch are Jiro Sekiba, Mitsuru Chinen, Masahide Washizawa, and Isamu Hasegawa.

"TERM is an environmental variable which tells the command interpreter (or the shell, bash in this case) how to behave," explains Steve Fox of the LTC. "vt100 is one of these settings and xterm is another. This update fixes the I18N support for people running the shell in a different mode."

LUI
The Linux Utility for cluster Installation has released version 1.11.1. LUI is a utility that installs workstations remotely over an ethernet network by providing tools to manage installation resources on the server. The LUI release notes read as follows:

• PowerPC rpm Installation -- A workaround is provided to enable PowerPC rpm installation on SuSE 7.1 PowerPC edition.
• postinstall bug fix -- Changed code in clone to execute postinstall script located in /tftpboot/tar.
• Command fix -- Ignore spaces in resource/machine names.

Read the previous bulletin for information on the merger between LUI and the VA SystemImager to form SIS, the System Installation Suite.

Linux for S/390
The Linux for S/390 team has new experimental patches for Linux 2.4.5. "This is the first set of patches for the 2.4.5 Linux kernel on S/390," Steve Fox notes. "They are experimental so far and have not been thoroughly tested."

Linux for S/390 is a port of Linux to the S/390 architecture. It is a pure Linux from a user point of view. It supports the S/390 processor architecture and some devices that are specific to S/390 environments. S/390 is IBM's standard bearer for enterprise computing.

Global spinlock list and usage
Rick Lindsley has updated his "Global spinlock list and usage" document for the 2.4.5 kernel. "The locking document provides, for the first time in modern Linux, a list of the global spin locks that are available," Rick comments, "and, when possible, under what conditions it is appropriate for a coder to use them. The document is current for Linux 2.4.5 and is intended to be kept up-to-date on a regular (though not constant) basis."

Rick has over twenty years experience working on Unix systems, the last ten being at Sequent Computers, now IBM. At the Linux Technology Center he now puts to use the exposure to SMP (Symmetric multi-processing) systems that he picked up at Sequent and applies it to Linux. While his current efforts are focused on improving the locking document, he's also jointly responsible for the SMP HOWTO document with the Linux Documentation Project. In the past year he has also been speaking to Linux User Groups in Washington and Canada about IBM's commitment to Linux.

OpenLDAP
The OpenLDAP project team has released patches for NLS support. "This patch," the authors Julius Enarusai and Shailabh Nagar explain, "provides National Language Support to OpenLDAP. More specifically, it provides the ability to retrieve LDAP error and informational messages from an XPG4-compliant catalog in the user's national language and the ability for LDAP client applications developers to customize LDAP error and informational messages."

OpenLDAP is an implementation of the Lightweight Directory Access Protocol, which defines protocols for updating and searching directories running over TCP/IP. It was designed by the Internet Engineering Taskforce to encourage use of the standard X.500 directories from the International Telecommunications Union, covering electronic directory services.

JFS
The Journaled File System technology for Linux has released version 1.0, which will be presented in more detail in the next LTC bulletin. "Previous to this, drop 35-37 included fixes to the file system and utilities," according to Steve Best, the project's maintainer. "There is now a patch that will make it easier to move from release 0.3.4 to 0.3.5, the patch file is called jfs-0_3_4-to-0_3_5.patch.gz." The release notes for drop 35 to 37 read as follows:

0.3.5

• Updated fsck error handling
• Updated mkfs config options and the man page for fsck
• Increased the performance of unlinking files; most unlinks are done asynchronously now
• Fixed "XT_GETPAGE: xtree page corrupt" when creating files on nfs mounted partition

0.3.6

• Fixed jitterbug problem # 10 rm -rf fails on a big directory

0.3.7

• Fixed find_entry called with index = 0 or 1 (jitterbug #126)
• Fixed the rm -rf case where if files weren't created sequential then the rm -rf didn't work correctly

The Journaled File System technology from IBM, currently used in its enterprise servers, provides a log-based, byte-level file system designed for high-throughput server environments. Work is underway to complete the port to Linux.

Samba
The Samba team has released new patches for Win9x client permissions viewing and Lanman 2.1 dialect API support. Jim McDonough has been posting Samba patches for a while now, which enhance OS/2 support as well as user and file permission management.

The patch for Win9x client permissions has been updated so that permissions can be manipulated as well. "This patch first allowed Windows 9x users to install the Windows NT Server Tools (from the Windows NT Server CD) and view file and folder permissions," according to Jim McDonough. "It then added the capability of changing the permissions by implementing two new RPCs on the srvsvc (Server Services) pipe, numbers 0x27 and 0x28. Implementing these RPCs has been a major focus of the team, as this is how much of the NT wkst wkst, srvr wkst, and srvr<->srvr communications are implemented."

The Lanman patch adds certain Lanman 2.1 dialect APIs to the client side. It was done on behalf of Luciano Chavez, who did the original work. Jim McDonough updated the recent release.

Distributed Lock Manager
The Distributed Lock Manager project has released version 0.4. The release notes state that this version "consists of several fairly major changes to the DLM. The net result of these changes is that the DLM can now handle node leave/join recovery and can perform distributed locking operations. " Among these changes are:

• The recovery state machine (implemented in clm_main.c and clm_reconfig.c) was completely re-implemented. As Ian Romanick, one of the project leaders, explains, "The internal workings of the DLM were rewritten and restructured to improve readability and to greatly simplify ongoing maintenance. We also eliminated obsolete function. The semantics and operations of the DLM were not modified."
• Nearly all of the memory management routines were changed to use kmem_cache_t's. "The internal memory management routines of the DLM were brought into better alignment with normal and expected mechanisms in Linux," says Romanick, "and obsolete mechanisms were eliminated."
• Nearly all of the GCC warnings (mostly related to printk and bsdlog format strings) were fixed.

"The big picture is that this release of the DLM actually supports reasonable usage across multiple nodes and supports client usage," explains Ian. "Not that every bug is cleaned up, but at least this sets the stage for more strenuous testing and work on the DLM."

"The DLM," the team explains, "provides an implementation of the classic VAX Cluster locking semantics for a Linux cluster. Clients that wish to use the locking facilities connect through an API embodied in a shared library. The DLM handles recovery from failure of various components within the cluster."

Omni
The Omni project has released versions 0.3.0 and 0.3.1.

From the changelog for 0.3.0:

• Changed the way to create a new dither instance to allow for future growth/other dither packages

"The dither routines," according to Mark Hamzy, a member of the Omni project team, "were hard coded to have a certain number of parameters. We gathered the parameters into one string of key=value entries. Now a different dither routine can have different parameters."

• Fixed FORM_LEDGER's size to be 17x11 to conform with Ghostscript

"The omni driver had the wrong size for Legder," Mark explains. "The Ledger form (17x11) is a rotated Legal (11x17) form."

• Added 10 new Medias to encompass the PWG's UPDF format
• Added initial code to handle a UPDF device XML. The omni driver is working with the Printer Working Group's (PWG) Universal Printer Description File (UPDF) standard
• Switched from dlopen to glib's version

"The omni driver is composed of two parts," Mark notes. "The first part is a set of core routines that is bundled into libomni.so. The second part is a device library for each device that the omni supports (for example, libEpson_Stylus_Color_760.so). These libraries were loaded and accessed with the dynamic linking loader (dl). The omni driver switched to gnome's library (glib), which has the same set of routines and is supported on more platforms."

From the changelog for 0.3.1:

• Fixed build break in Canon BJC-8500 Blitter.cpp
• Fixed build break in tools directory

Omni edits old device description files in order to create new devices and allows for the subclassing of previous device features, which simplifies printer driver development.

DProbes and GKHI
Richard Moore, from the DProbes and GKHI projects, presented three papers recently at the UKUUG Linux Developers Conference 2001 and the USENIX Annual Technical Conference. The papers are available on the LTC White Papers Web page. The two main themes he covered in the papers were Universal Dynamic Tracing for Linux and other operating systems, and Generalised Kernel Hooks for the Linux Kernel. As the RAS architect at the LTC, Richard Moore is responsible for leading serviceability initiatives for Linux and is a leader of the DProbes Project.

"I discussed in detail the features of DProbes that makes universal dynamic tracing feasible," Richard says. "Also how Dprobes could be ported to other hardware architectures and other operating systems.

"Quite a lot of interest was expressed. Interestingly, I was asked whether a port to BSD would be feasible and whether we had considered using DProbes to drive a hardware debugging monitor. Although neither of these ideas is in plan, I would be interested in working offline with anyone who wants to port DProbes to BSD."

The Generalized Kernel Hooks were discussed at the UKUUG conference. "This talk was very interactive," notes Richard. "I put forward an idea to launch an open source project to use GKHI as a framework for implementing dynamic assertion checking within drivers and the kernel."

DProbes is a debugging facility designed to work under extreme or inaccessible conditions. It gathers diagnostic information by dynamically firing probes into executing code modules, relying on user written probe-handlers (programs written in assembly-like code based on Reversed Polish Notation).

The GKHI generalized mechanism manages exits in kernel space; it is suitable for use in first failure data capture applications, security hooks, and optional serviceability tools.

iSeries
The iSeries team has updated the 2.4.3 kernel patches for the iSeries. The updates include:

• SMP stability improvements
• Clock and VIODASD fixes; VIODASD describes how Linux on LPAR accesses the hard drive
• Fixes for JVM support (Java virtual machine used to run Java applications)
• VIOTAPE (tape drive) and VIOCD (CD-ROM) fixes
• System clock given default value if none set

The IBM e-server iSeries is a set of enterprise servers designed for e-business solutions. Although Linux distributions for the iSeries are yet to be made available, you can run Linux on the iSeries unsupported. Note that this requires the next version of OS/400, which is still in beta testing.

Events
The LTC's Upcoming events page has been updated to include the CIFS 2001 Conference in Bellevue, Washington, on August 21 - 22. Steve French of the LTC will present a paper on next generation SMB/CIFS client filesystem at the conference.

Resources

• Read the previous LTC bulletins on developerWorks:
  • June 19, 2001
  • May 21, 2001
  • May 7, 2001
  • April 23, 2001
• Visit the Linux Technology Center and take a look Behind the scenes at the LTC.
• Browse the Linux Documentation Page.
• Learn more about the projects and patches covered in this LTC bulletin:
  • Distributed Lock Manager project (developerWorks)
  • DProbes project (developerWorks)
  • EVMS project (SourceForge)
  • GKHI project (developerWorks)
  • Global spinlock list and usage by Rick Lindsley (SourceForge)
  • Internationalization patches for GNU bash (developerWorks)
  • iSeries project (developerWorks)
  • JFS project (developerWorks)
  • Linux for S/390 project (developerWorks)
  • Linux System RAS project (SourceForge)
  • LUI project (developerWorks)
  • Omni project (developerWorks)
  • OpenLDAP project (developerWorks)
  • Samba project (developerWorks)
• Take our free JFS fundamentals tutorial.
• Check out more Linux resources and more Open source resources on developerWorks.

About the author
Maya Stodte is a contributing writer and editor for developerWorks. She can be reached at mstodte@us.ibm.com.

Copyright 2001