Process Dump Reference 26 Aug 2005 ---------------------- Steven H. Levine steve53@earthlink.net 0. Introduction. ------------- This note explains how to set up and record process dumps and how to do basic dump analysis. 1. Setup. ------ There are several ways to enable and configure the process dump facility. Pick the one that best suits you needs. To enable the process dump facility permanently, add the following line to CONFIG.SYS: DUMPPROCESS=x where x is the drive where you want to store the dump files. After you reboot, the kernel will generate a dump file for every program that traps. The file will be stored in the root of the drive. Depending on how the program uses memory, dump files can be very large so pick a drive with sufficient free space. For best results pick the JFS or HPFS drive with the most free space. For more information on the DUMPPROCESS command, type view cmdref dumpprocess from the command line. To activate the process dump facility from the command line, issue the command: procdump on /l:pathname where pathname is the drive or directory where you want to store the dump files. After you enter this command, the kernel will generate a dump file for every program that traps. This setting will stay in effect until you turn it off or until you reboot. To create a onetime dump of a running program, issue the commands: procdump on /l:pathname procdump force /proc:processname procdump off where pathname is the drive or directory where you want to store the dump file and processname is the name of the process to be dumped. After you enter these commands, the kernel will generate a single dump file for the named process. The default settings generate a relatively small dump file, but might not include sufficient detail for analysis. If you need all the process memory included in the dump file, enter the command: pdumpusr private,update before generating the dump file. If you need all the shared memory included in the dump, enter the command: pdumpusr private,shared,update before generating the dump file. There are cases where the dump facility will hang or trap when attempting to dump shared memory. If this occurs, try the alternate command: pdumpusr paadr(all),update This will generate a dump file slightly larger than the quantity of physical memory, but it is usually sufficient to generate a usable dump file. For more information on the pdumpusr options, see \os2\system\ras\procdump.doc 2. Recording Process Dumps. ------------------------ Once you have enabled the dump facility, the kernel will a generate dump file for each trap that occurs or whenever you use the FORCE option. If you are getting frequent traps, turn off the dump facility as soon as possible to avoid filling up your disk. To turn off the dump facility from the command line, enter the command: procdump off If you enabled the dump facility from CONFIG.SYS, don't forget to REM out the line in CONFIG.SYS when you no longer need to collect the dump files. 3. Preparing to Use the PM Dump Facility. -------------------------------------- The PM Dump Facility (PMDF) is a generic tool which needs to be configured to understand the dump files generated by a specific kernel version. PMDF is configured with a set of files known as .sym files. The .sym files contain tables used to translate binary addresses to symbolic labels. The .sym files includes two kernel specific EXEs (DF_RET.EXE and DF_DEB.EXE) These EXEs understand the layout of the kernel data structures and are considered part of the .sym file set. The .sym file set is kernel version specific, FixPak specific and application version specific Assuming a standard install of the Dump Facility, the .sym files are stored in a subdirectory of \os2\pdpsi\pmdf on your boot drive and pointed to by the index file \os2\pdpsi\pmdf\pmdfvers.lst. Depending on what components you installed when you installed Warp on the box where the trap occurred, you might already have the files needed to examine the dump installed in \os2\pdpsi\pmdf\merlin. If not, the following examples describe how to get the files you need and how to install the files so that PMDF can use them. The examples that follow assume: FixPak 15 Kernel version 14.062 Boot drive f: Be sure to replace the values shown in the examples with values that match your specific system. This applies to kernel revision numbers, boot drive letters and other values that are specific to your system. Add pathname prefixes as needed to match where you have stored the files. If you are not sure of what kernel revision you are running, use your favorite hex editor and search for the string "Internal revision" without the quotes. The string that follows is the value PMDF uses to match the kernel to the symbols. You can find the same information with: bldlevel f:\os2krnl but the revision number reported in the build level string is usually not in exactly the format that PMDF is looking for. Go to: ftp.software.ibm.com/ps/products/os2/fixes/debug and download m015dmp.zip. This is the symbols zip file for FP15 and kernel version 14.062. If you are using a testcase kernel, the dump symbols will be at: testcase.boulder.ibm.com/ps/fromibm/os2 and will be named: dfyyyymmdd.zip where mmdd matches the testcase kernel date. When you download a testcase kernel, be sure to download the symbols file at the same time. Otherwise, it might be gone when you need it. Create the subdirectory: f:\os2\pdpsi\pmdf\warp4.15 Unzip the contents of m015dmp.zip into this subdirectory with: unzip -j m015pmd.zip -d f:\os2\pdpsi\pmdf\warp4.15 This will put all the files in m015pmd.zip into a single directory. This is important. If you don't use the -j option or it's equivalent, the Dump Facility will not be able to find the symbols. The zip files are structured for use with either the Kernel Debugger or PMDF. The Kernel Debugger requires that the .sym files be in the same directory as the associated executable. The zip files contain subdirectory information so that the files will be placed in the correct directory when unzipped. PMDF has different requirements. For PMDF, the .sym file sets must be in a subdirectory named in pmdfvers.lst. The Kernel Debugger runs on the Machine Under Test (MUT). The only set of symbols it needs, or can use, are the one's for the installed kernel revision. PMDF is often run on a system other than the MUT which generated the dump. Using pmdfvers.lst to locate the correct symbols for the dump allows PMDF to be used to analyze dumps even when the systems have different kernel revisions installed. Pmdfvers.lst will have a line defining where to find the symbols for each specific kernel revision to be analyzed. Add the following line to pmdfvers.lst: warp4.15:14.062:OS/2 Warp 4 FP15 warp4.15 is the directory you unzipped the symbols. 14.062 is the internal version string for the kernel. The version string is case sensitive and must match exactly. The rest is a comment to help you remember what the other two values mean. This will allow PMDF to automatically find the symbols for the 14.062 kernel in the warp4.15 subdirectory. If your application came with .sym files copy them into this directory. If your application came with .map files, use the mapsym utility to create the .sym files. Mapsym is available with most compilers. If you need usage help, just type: mapsym from the command line. If you don't have either .map or .sym files for your application, it may be a bit more difficult to analyze the dump file, but PMDF will still work. When editing pmdfvers.lst, make sure you don't have any blank lines otherwise pmdf will trap on startup. Thanks go to Lars Erdmann for this tip. 4. Analyzing Process Dumps. ------------------------ This is the bare bones. Start PMDF. For Warp4, you should have an object in the Problem Determination Tools folder. For eCS, the object should be in the Utilities folder. If you don't have an object, you can start PMDF from the command line. If you didn't install PMDF, you will need to run Selective Install and install the Problem Determination Tools and reapply the last FixPak you installed (i.e. FP15 or whatever). From the PMDF File menu, open the dump file. PMDF should find the matching .sym files, using the data in pmdfvers.lst. If for some reason PMDF cannot match up the dump file and the .sym files, it will prompt you to select a .sym file set from the sets defined in pmdfvers.lst. Since you configured PMDF above, this should not occur. You can try selecting one of the available .sym file sets, but the results will be unpredictable. PMDF may misinterpret the dump file content or it may even trap. From Analyze menu, select Synopsis -> Trap Screen. From Analyze menu, select Thread -> Ring 3 Stack Trace. From Analyze menu, select Process -> Open Files From Analyze menu, select Process -> Module Table. From the PMDF command line at the bottom of the window, enter the commands: r ln u eip-20 eip k dd ebp Press the Enter key after each command. From the File menu, select Save Output and save the window contents to a file. If you don't understand what you are seeing, you will have to find someone to help you interpret the content of the dump file. Ask questions and let your helper guide you. Be prepared to spend some time working with your helper to understand the cause of the trap. The bare bones information you generated is just a starting point. It may or may not be sufficient to identify the source of the trap. Unless you are lucky, your helper will request additional output and may ask you generate another dump file using different settings. Often, your helper will to want you to send a copy of the dump file and the debug symbols. It is a good idea to keep notes describing how each dump file was generated and what you were doing when the dump file was generated. This is especially important for intermittent failures where one is looking for a pattern. Save the dump file, the debug symbols and your notes until analysis is complete. 5. E-mailing Process Dumps. ------------------------ In general, don't e-mail a dump file to someone without asking them if they want you to send it. If you do need to e-mail the file, zip it up first. This will save transmit time and protect the dump file from corruption. It's always a good idea to give the zip file a useful name. Something like DavesTrapE_20040501.zip will help everyone remember what the zip file contains. It's also a good idea to include a note in the zip file describing how and why the trap occurred along with the bldlevel output. The zip file may get separated from the e-mail message. You should include the output of procdump query in your note. This will describe the type of data recorded in the dump file. If the zip file is over 5MB or so, check with your helper before sending the e-mail. You may need to use a file splitter and send each chunk in a separate e-mail giving your helper a chance to delete each e-mail from the server before you send the next chunk. Most ISPs limit e-mail inboxes to 10MB and unless you send the zip file in chunks, it will never get to your helper. If you can arrange to FTP the zip file to your helper, this is often a better solution. Be careful to send the e-mail containing the dump file only to the intended addressee. Sending a large, unexpected e-mail to all the members of a mailing list, some of whom may still be one dial up, is sure of upset someone. Good luck. Steven