Microsoft KB Archive/138258

= Windows NT Debug Symbol Setup Information =

Article ID: 138258

Article Last Modified on 11/1/2006

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APPLIES TO


 * Microsoft Windows NT Advanced Server 3.1
 * Microsoft Windows NT Server 3.5
 * Microsoft Windows NT Server 3.51
 * Microsoft Windows NT Server 4.0 Standard Edition
 * Microsoft Windows NT Workstation 3.1
 * Microsoft Windows NT Workstation 3.5
 * Microsoft Windows NT Workstation 3.51
 * Microsoft Windows NT Workstation 4.0 Developer Edition
 * Microsoft Windows NT Advanced Server 3.1

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This article was previously published under Q138258



SUMMARY
This article provides detailed information on how to set up Microsoft Windows NT Symbol Trees, as well as advanced setup tips and tricks.



Article Contents

 * General Information
 * Setting up Custom Symbol Trees
 * Single Processor vs. Multi Processor
 * Custom HAL.DLL
 * Using Symbols in Debugger
 * Verifying the Symbols
 * Advanced Symbol Verification
 * Checked Versions

General Information
Debug Symbol files (symbols) are required to do both kernel and user-mode debugging in Windows NT. Symbols provide a way to reference global variables and function names in the loaded executable.

Symbols are produced by the linker. They are stripped out of retail product and saved in a separate (.DBG) file. This considerably reduces file size which decreases file load time and thus increases system performance. It also reduces the number of install floppies. Symbols represent Function/API names and global variables.

The .DBG File contains symbolic information for each file. They can be found on the installation CD-ROM in \Support\Debug\[i386 | mips]\Symbols. They can also be found on the NT build server. The location is \\Ntbuilds\Release\Usa\Build###\[x86 | mips |alpha]\Fre.srv\symbols.

The Symbols directory is divided up into seven subdirectories, called Extension Subdirectories (note that many of the symbol files in these directories are User mode):

COM - symbols for all files ending in .COM go here

CPL - symbols for all files ending in .CPL go here.

DLL - symbols for all files ending in .DLL go here

DRV - symbols for all files ending in .DRV go here

EXE - symbols for all files ending in .EXE go here

SCR - symbols for all files ending in .SCR go here

SYS - symbols for all files ending in .SYS go here.

Symbols must match file versions:

Symbols from a different build give erroneous information and send developers chasing shadows and waste considerable time. Double check with the customer what build the customer is running and if the customer has any patches installed. The Kernel Stop Screen displays the build number of the kernel.

Patched Builds:

Patched builds such as Service Packs require a special set of symbols, that is a combination of the base build and the patched symbols.

Setting Up Custom Symbol Trees
Remember that symbols must match the files installed on a customer's computer. You often have to create a custom set of symbols just for a particular customer.

NOTE: Complete Symbol Trees can take up over 30 MB of disk space.


 * 1) Create a subdirectory to store your customer symbol set. For example:

C:\MYSYMBOLS
 * 1) Always start with the base Windows NT version number. Copy the following files from the installation CD-ROM for the appropriate version:

XCOPY [CD Drive]\SUPPORT\DEBUG\I386 C:\MYSYMBOLS /S.
 * 1) Copy symbols for the appropriate Service Pack binary files over your custom tree. Service Pack symbols can be found on the servers listed in the section below titled "Symbol Locations."
 * 2) Copy any third-party patches such as Compaq SSD symbols over to your custom symbol tree. You may need to get these symbols from the vendor. NOTE: Steps 3 and 4 may need to be reversed depending on the order that they were installed by the customer. Match the customer's steps.
 * 3) If the server has hotfixes installed, you need to obtain the matching symbol for that hotfix. If a symbol file is not provided with the hotfix, you need to contact Microsoft Product Support Services to inquire about the availability of these symbols. Copy the updated symbol over your custom symbol tree. Make sure that you place it in the correct subfolder (for example, Sys, exe, dll, etc.).

Single Processor vs. Multi Processor
Windows NT uses a special kernel for SMP systems. During installation this kernel is renamed. It is important that you also rename the SYMBOL.DBG file for debugging.

NTOSKRNL.EXE NTOSKRNL.DBG = Single processor NTKRNLMP.EXE. NTKRNLMP.DBG = Multiple processors


 * 1) If you have a multi-processor system do the following. Under your custom symbol tree in \SYMBOLS\EXE there are two kernel files. Rename NTOSKRNL.DBG to NTOSKRNL.UNI.
 * 2) Copy NTKRNLMP.DBG to NTOSKRNL.DBG.

Custom HAL.DLL
Some hardware platforms require a special Hardware Abstraction Layer Driver. Like the Kernel file, the custom HAL is renamed during the installation process. Here is a list of common HALs:

HAL files for I386 Computers:

             Uncompressed Filename     Size (bytes) Description - HAL.DLL      48,416       Standard HAL for Intel systems HAL486C.DLL  47,376       HAL for 486 c step processor HALAPIC.DLL  63,616       Uniprocessor version of HALMPS.DLL HALAST.DLL   46,416       HAL for AST SMP systems HALCBUS.DLL  79,776       HAL for Cbus systems HALMCA.DLL   45,488       HAL for MCA-based systems (PS/2 and others) HALMPS.DLL   65,696       HAL for most Intel multiprocessor systems HALNCR.DLL   79,392       HAL for NCR SMP machines HALOLI.DLL   40,048       HAL for Olivetti SMP machines HALSP.DLL    52,320       HAL for Compaq Systempro HALWYSE7.DLL 40,848       HAL for Wyse7 systems

HAL files for DEC Alpha Computers:

Uncompressed Filename     Size (bytes) Description -- HAL0JENS.DLL 56,800       Digital DECpc AXP 150 HAL HALALCOR.DLL 69,120       Digital AlphaStation 600 Family HALAVANT.DLL 66,752       Digital AlphaStation 200/400 Family HAL HALEB64P.DLL 70,528       Digital AlphaPC64 HAL HALGAMMP.DLL 72,896       Digital AlphaServer 2x00 5/xxx Family HAL HALMIKAS.DLL 67,040       Digital AlphaServer 1000 Family Uniprocessor HAL HALNONME.DLL 65,376       Digital AXPpci 33 HAL HALQS.DLL    65,088       Digital Multia MultiClient Desktop HAL HALSABMP.DLL 72,736       Digital AlphaServer 2x00 4/xxx Family HAL

HAL files for MIPS Computers:

Uncompressed Filename     Size (bytes) Description -- HALACR.DLL   43,648       ACER HAL HALDTI.DLL   68,288       DESKStation Evolution HALDUOMP.DLL 41,728       Microsoft-designed dual MP HAL HALFXS.DLL   42,016       MTI with a r4000 or r4400 HALFXSPC.DLL 42,176       MTI with a r4600 HALNECMP.DLL 44,736       NEC dual MP HALNTP.DLL    116,000      NeTpower FASTseries HALR98MP.DLL 127,232      NEC 4 processor MP HALSNI4X.DLL  95,520       Siemens Nixdorf UP and MP HALTYNE.DLL   68,032       DESKstation Tyne

HAL files for PPC Computers:

Uncompressed Filename     Size (bytes) Description -- HALCARO.DLL  169,504      HAL for IBM-6070 HALEAGLE.DLL 206,208      HAL for Motorola PowerStack and Big Bend HALFIRE.DLL  136,576      Hal for Powerized_ES, Powerized_MX, and Powerized_MX MP HALPOLO.DLL  169,152      HAL for IBM-6030 HALPPC.DLL   169,184      HAL for IBM-6015 HALWOOD.DLL  95,616       HAL for IBM-6020

How to Determine Which HAL to Use:

During installation a text log file is created. This file can inform you about the original name of the HAL.


 * 1) Go to %systemroot%\REPAIR subdirectory.
 * 2) Run ATTRIB -R -H -S SETUP.LOG to make the file visible.
 * 3) Bring up the file in Microsoft Notepad and search for HAL.

NOTE: This same technique can be useful to verify if a special kernel is also used.

Go to Setup HAL Symbol:


 * 1) Go to your custom symbol tree under \SYMBOLS\DLL.
 * 2) Rename HAL.DBG to HAL.X86.
 * 3) Copy the "Custom HLL.DBG" to HAL.DBG.

Using Symbols in the Debugger
A Windows NT Debugger, such as I386KD.EXE, looks for symbols in the following locations:

_NT_ALT_SYMBOL_PATH system environment variable

_NT_SYMBOL_PATH system environment variable

These locations are set via system environment variables. They are usually configured by a debug batch file using the SET command. The _NT_ALT_SYMBOL_PATH is optional. For example:

set _NT_SYMBOL_PATH=K:\NT35-SP3\SYMBOLS

set _NT_ALT_SYMBOL_PATH=c:\WINNT\SYMBOLS

NOTE: The symbols directory is the directory directly above the extension subdirectories (that is, if the kernel symbol file, NTOSKRNL.DBG, is located at C:\DEBUG\511\I386\SYMBOLS\EXE\NTOSKRNL.DBG. The _NT_SYMBOL_PATH should be set to C:\DEBUG\511\I386\SYMBOLS

How to Use Paths:

A good use of these various paths is for keeping static symbol trees for each Windows NT version. You simply point your symbol paths to each version and Service Pack as needed. For example, for a 1057 system with SP2 installed you could use the following:

set _NT_ALT_SYMBOL_PATH=c:\NT351-SP2\SYMBOLS

set _NT_SYMBOL_PATH=K:\NT351-1057\SYMBOLS

The debugger attempts to use the Service Pack symbols first. [The Service Pack symbols do not include the base build symbols in this case, only the SP symbols.] If the debugger does not find a particular symbol in the SP tree it looks it up in the 1057 symbol tree.

Search Order:

The various symbol paths are searched in the order listed above. The first symbol file with the correct name that is encountered is used. In the example above, _NT_ALT_SYMBOL_PATH=c:\NT351-SP2\SYMBOLS is the first one searched.

Environment Variable Override:

I386KD supports a command line switch "-y" where you can specify a symbol path. However, using this switch overrides your existing environment variables.

Change Path on the Fly:

You can change the symbol search path at any time in the debugger by issuing "!Sympath" command. For example:

!SYMPATH C:\SYMBOLS.

Verifying the Symbols
!RELOAD:

Once you have gotten to the "kd>" prompt for the first time, you must type "!RELOAD". This causes the symbolic information to be reloaded and synchronized. If you get the error "PsLoadedModuleList is NULL!", you probably have the wrong symbols loaded. Be sure you have the correct HAL.DBG and NTOSKRNL.DBG file installed for the computer that you are debugging.

!PROCESS:

Symbols can also be verified by typing "!PROCESS" if you get the error, "Can't find process list head", you probably have the wrong symbols loaded.

KB:

If the Stack Trace has gaps in the function name list, this indicates that you are missing symbols. Missing functions could also indicate a corrupt stack but this is somewhat rare. Double check your symbols before declaring a corrupt stack. Also, look at the return addresses on the stack. They should all be greater than 8000000.

!SYMPATH:

Incorrect symbols can be corrected by going to another command window, copying the correct symbols and doing a !reload on the debugger or by specifying the correct path with !SYMPATH.

Advanced Symbol Verification
Sometimes customers do not know what driver versions they have installed on their computers. Perhaps they installed a hotfix for NTFS but they do not know which bug number. You may need to manually determine which .DBG files are needed.

The best way to absolutely verify if target and dbg's match is to view their check sum value. This value is stored inside the file header.

Note: To learn more about operating system file format search MSDN for "Portable Execution File Format." The PE header contains version numbers, link date\time, etc.

The general plan here is to first find out the check sum of the customers files and then find a dbg file that has a matching check sum.

There are many ways to extract the chksum from the target and the dbg. If you have access to the files, you can use the following. This example assumes you are interested in the file NTOSKRNL.

LINK32:

This utility can be found in the NT Build subdirectory \MSTOOLS:

LINK32.EXE -DUMP -HEADERS NTOSKRNL.EXE LINK32.EXE -DUMP -HEADERS NTOSKRNL.DBG

DUMPBIN:

This utility can be found in the Visual C bin directory:

DUMPBIN.EXE /HEADERS NTOSKRNL.EXE DUMPBIN.EXE /HEADERS NTOSKRNL.DBG

If you are using a debugger on a system or a crash dump, you can find the checksum of the target file by viewing the file header in memory.


 * 1) !DRIVERS - Will give you driver base address.
 * 2) dd baseaddr+d8 L1

Checked Versions
If you install debug checked versions of Windows NT files you need to make special arrangements for they dbg symbol files. Some hotfix checked builds have the symbolic information built into the target file. In these cases, just make a copy of the file and name it *.DBG. Place the file in the normal symbol sub directory, that is, \SYMBOLS\EXE.

All publicly released check builds have separate dbg files just like the free releases. However, the dbg for checked and free versions are different. For example, the MS NT DDK contains a complete checked build of NT. It also contains a complete symbol set to go with it.

NOTE: Checked versions of the NT kernel are the same for both Multiprocessor and Uniprocessor systems.

Symbol Locations
Retail Product:

CD-ROM \SUPPORT\DEBUG\I386\SYMBOLS

\\NTX86X\FREEBINS.XXX

Additional query words: prodnt debugref

Keywords: kbusage KB138258

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