Livekd Could Not Resolve Symbols For Ntoskrnl.exe


Jul 11, 2006  Whenver I run livekd (whether I use use kd.exe or windbg.exe), it fails with the error, 'Could not resolve symbols for ntoskrnl.exe.' This is odd, because the symbol store seems to be working correctly in all other instances. If I open an executable with windbg, I can see that it downloads and resolves the symbols for various linked microsoft dlls. Cara Download Di Kshowonline Lewat Hp; Cara Download Dari Kshowonline Lewat Hp; Udah pada tau SNSD / Girls' Generation / Soshi kan? Gak usah pake basa basi, disini ane bukan mau bahas tentang soshi, tujuan thread ini adalah berbagi link download variety show yang pernah dihadiri sama SNSD.

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Symbol problems can show up in a variety of ways. Perhaps a stack trace shows incorrect information or fails to identify the names of the functions in the stack. Or perhaps a debugger command failed to understand the name of a module, function, variable, structure, or data type.

If you suspect that the debugger is not loading symbols correctly, there are several steps you can take to investigate this problem.

First, use the lm (List Loaded Modules) command to display the list of loaded modules with symbol information. The most useful form of this command is the following:

If you are using WinDbg, the Debug Modules menu command will let you see this information as well.

Pay particular attention to any notes or abbreviations you may see in these displays. For an interpretation of these, see Symbol Status Abbreviations.

If you don't see the proper symbol files, the first thing to do is to check the symbol path:

If your symbol path is wrong, fix it. If you are using the kernel debugger make sure your local %WINDIR% is not on your symbol path.

Then reload symbols using the .reload (Reload Module) command:

If your symbol path is correct, you should activate noisy mode so you can see which symbol files dbghelp is loading. Then reload your module. See Setting Symbol Options for information about how to activate noisy mode.

Here is an example of a 'noisy' reload of the Microsoft Windows symbols:

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The symbol handler first looks for an image that matches the module it is trying to load (lines three and four). The image itself is not always necessary, but if an incorrect one is present, the symbol handler will often fail. These lines show that the debugger found an image at D:MyInstallationi386ntkrnlmp.exe, but the time-date stamp didn't match. Because the time-date stamp didn't match, the search continues. Next, the debugger looks for a .dbg file and a .pdb file that match the loaded image. These are on lines 6 through 10. Line 11 indicates that even though symbols were loaded, the time-date stamp for the image did not match (that is, the symbols were wrong).

If the symbol-search encountered a catastrophic failure, you would see a message of the form:

This could be caused by items such as file system failures, network errors, and corrupt .dbg files.

Diagnosing Symbol Loading Errors

When in noisy mode, the debugger may print out error codes when it cannot load a symbol file. The error codes for .dbg files are listed in winerror.h. The .pdb error codes come from another source and the most common errors are printed in plain English text.

Some common error codes for .dbg files from winerror.h are:




It's possible that the symbol file cannot be loaded because of a networking error. If you see ERROR_BAD_FORMAT or ERROR_BAD_NETPATH and you are loading symbols from another machine on the network, try copying the symbol file to your host computer and put its path in your symbol path. Then try to reload the symbols.

Verifying Your Search Path and Symbols

Let 'c:MyDir;c:SomeDir' represent your symbol path. Where should you look for debug information?

In cases where the binary has been stripped of debug information, such as the free builds of Windows, first look for a .dbg file in the following locations:


Next, look for a .pdb file in the following locations:

Note that in the search for the .dbg file, the debugger interleaves searching through the MyDir and SomeDir directories, but in the .pdb search it does not.

Windows XP and later versions of Windows do not use any .dbg symbol files. See Symbols and Symbol Files for details.

Mismatched Builds

One of the most common problems in debugging failures on a machine that is often updated is mismatched symbols from different builds. Three common causes of this problem are: pointing at symbols for the wrong build, using a privately built binary without the corresponding symbols, and using the uniprocessor hardware abstraction level (HAL) and kernel symbols on a multiprocessor machine. The first two are simply a matter of matching your binaries and symbols; the third can be corrected by renaming your hal*.dbg and ntkrnlmp.dbg to hal.dbg and ntoskrnl.dbg.

To find out what build of Windows is installed on the target computer, use the vertarget (Show Target Computer Version) command:

Testing the Symbols

Testing the symbols is more difficult. It involves verifying a stack trace on the debugger and seeing if the debug output is correct. Here's one example to try:

The u command unassembles the videoportfindadapter string in videoprt.sys. The symbols are correct on the debugger because common stack commands like push and mov show up on the stack. Most functions begin with an add, sub, or push operation using either the base pointer (ebp) or the stack pointer (esp).

It's usually obvious when the symbols aren't working correctly. Glintmp.sys doesn't have symbols in this example because a function isn't listed next to Glintmp:

The wrong build symbols were loaded for this stack trace. Notice how there are no functions listed for the first two calls. This stack trace looks like a problem with win32k.sys drawing rectangles:

Here's the correct stack trace. The problem is really with AGP440.sys. The first item appearing on a stack trace is usually at fault. Notice that the win32k.sys rectangle error is gone:

Useful Commands and Extensions

The following commands and extensions may be useful in tracking down symbol problems:

lm (List Loaded Modules)
Lists all modules and gives the loading status of all symbols in these modules.

!dh image-header-base
Displays header information for a loaded image beginning at image-header-base.

.reload /n
Reloads all kernel symbols.

.reload [image-name]
(CDB or WinDbg only) Reloads symbols for the image image-name. If no image-name is specified, reloads symbols for all images. (It is necessary to reload symbols after the symbol path has been changed.)

!sym noisy
Turns on verbose mode for symbol loads. This can be used to get information about the module loads. See Setting Symbol Options for details.

.sympath [new-symbol-path]
Sets a new symbol path, or displays the current symbol path. See Symbol Path for details.

If the kernel symbols are correct, but you aren't getting a complete stack, the following commands may also be useful:

X *!
This will list the modules which currently have symbols loaded. This is useful if the kernel symbols are correct.

.reload /user
This will attempt to reload all user-mode symbols. This is needed while performing kernel debugging if symbols were loaded while one process was running, and a break later occurred in another process. In this case, the user-mode symbols from the new process will not be loaded unless this command is executed.

X wdmaud!*start*
This will list only the symbols in the wdmaud module whose names contain the 'start' string. This has the advantage that it forces the reloading of all the symbols in wdmaud, but only displays those with 'start' in them. (This means a shorter listing, but since there are always some symbols with 'start' in them, there will be some verification that the load has taken place.)

One other useful technique for verifying symbols is unassembling code. Most functions begin with an add, sub, or push operation using either the base pointer (ebp) or the stack pointer (esp or sp). Try unassembling (U Function) some of the functions on the stack (from offset zero) to verify the symbols.

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Network and Port Problems

Problems will occur with the symbol files and while connecting to the debugger. Here are a few things to keep in mind if you encounter problems:

  • Determine which COM port the debug cable is connected to on the test system.

  • Check the boot.ini settings of the test system. Look for the /debug switch and check the baud rate and COM port settings.

  • Network problems can interfere with debugging if the symbols files are accessed through the network.

  • .dll and .sys files with the same name (for example − mga64.sys and mga64.dll) will confuse the debugger if they aren't separated into the proper directories of the symbol tree.

  • The kernel debugger doesn't always like replacing the build symbol files with private symbol files. Double check the symbol path and do a .reloadFileName on the misbehaving symbol. The !dlls command is sometimes useful.

Questions and Misconceptions

Q: I've successfully loaded symbols, but the stack seems to be wrong. Is the debugger broken?

A: Not necessarily. The most likely cause of your problem is that you've got incorrect symbols. Go through the steps outlined in this section to determine whether you've loaded valid symbols or not. Do not assume that because some things work you have valid symbols. For example, you very well may be able to execute dd nt!ntbuildnumber or u nt!KeInitializeProcess with incorrect symbols. Verify that they are correct using the procedures outlined above.

Q: Will the debugger still work with incorrect symbols?

A: Yes and no. Often you can get away with symbols that don't strictly match. For example, symbols from a previous Windows build will often work in certain cases, but there is no rule as to when this will work and when it will not.

Q: I'm stopped in the kernel debugger and I want to view symbols for my user-mode process. Can I do it?

A: Mostly. The support for this scenario is poor because the kernel debugger doesn't keep enough information around to track the module loads for each process, but there's a reasonable workaround. To load symbols for a user-mode module, execute a .reload -user command. This will load the user-mode modules for the current context.

Q:Player mp3 for mac. What does the following message mean?

*** WARNING: symbols checksum and timestamp is wrong 0x0036d6bf 0x0036ab55 for ntkrnlmp.exe

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A: It means your symbols for ntkrnlmp.exe are wrong.


Symbol Path

The symbol path specifies the directories where the symbol files are located. For more information about symbols and symbol files, see Symbols.

Note If you are connected to the Internet or a corporate network, the most efficient way to access symbols is to use a symbol server. You can use a symbol server by using the srv* or symsrv* string within your symbol path. For more information about symbol servers, see Symbol Stores and Symbol Servers.

To control the symbol path in WinDbg, do one of the following:

  • Choose Symbol File Path from the File menu or press CTRL+S.

  • Use the .sympath (Set Symbol Path) command. If you are using a symbol server, the .symfix (Set Symbol Store Path) command is similar to .sympath but saves you typing.

  • When you start the debugger, use the -y command-line option. See WinDbg Command-Line Options.

  • Before you start the debugger, use the _NT_SYMBOL_PATH and _NT_ALT_SYMBOL_PATH environment variables to set the path. The symbol path is created by appending _NT_SYMBOL_PATH after _NT_ALT_SYMBOL_PATH. (Typically, the path is set through the _NT_SYMBOL_PATH. However, you might want to use _NT_ALT_SYMBOL_PATH to override these settings in special cases, such as when you have private versions of shared symbol files.) If you try to add an invalid directory through these environment variables, the debugger ignores this directory.

    Note If you use the -sins command-line option, the debugger ignores the symbol path environment variable.

Executable Image Path

An executable file is a binary file that the processor can run. These files typically have the .exe, .dll, or .sys file name extension. Executable files are also known as modules, especially when executable files are described as units of a larger application. Before the Windows operating system runs an executable file, it loads it into memory. The copy of the executable file in memory is called the executable image or the image.

Note These terms are sometimes used imprecisely. For example, some documents might use 'image' for the actual file on the disk. Also, the Windows kernel and HAL have special module names. For example, the nt module corresponds to the Ntoskrnl.exe file.

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The executable image path specifies the directories that the binary executable files are located in.

In most situations, the debugger knows the location of the executable files, so you do not have to set the path for this file.

However, there are situations when this path is required. For example, kernel-mode small memory dump files do not contain all of the executable files that exist in memory at the time of a stop error (that is, a crash). Similarly, user-mode minidump files do not contain the application binaries. If you set the path of the executable files, the debugger can find these binary files.

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The debugger's executable image path is a string that consists of multiple directory paths, separated by semicolons. Relative paths are supported. However, unless you always start the debugger from the same directory, you should add a drive letter or a network share before each path. Network shares are also supported. The debugger searches the executable image path recursively. That is, the debugger searches the subdirectories of each directory that is listed in this path.

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To control the executable image path in WinDbg, do one of the following:

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  • Choose Image File Path from the File menu, or press CTRL+I.

  • Use the .exepath (Set Executable Path) command.

  • When you start the debugger, use the -i command-line option. See WinDbg Command-Line Options.

  • Before you start the debugger, use the _NT_EXECUTABLE_IMAGE_PATH environment variable to set the path.

    Note If you use the -sins command-line option, the debugger ignores the executable image path environment variable.

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