Saint's Log

Checking Symbol Availability on Windows OpenJDK Build

We use SymChk to ensure that symbols are available for Windows applications. For the OpenJDK build, this command line can be used to ensure the symbols directory contains symbols for all the Java binaries:

"C:\Program Files (x86)\Windows Kits\10\Debuggers\x64\symchk" /r D:\java\binaries\jdk\x64\jdk-17.0.7+7\ /s D:\java\binaries\jdk\x64\jdk-17.0.7+7-debug-symbols\bin;D:\java\binaries\jdk\x64\jdk-17.0.7+7-debug-symbols\bin\server

As per the SymChk Command-Line Options docs:

• /r causes SymChk to recursively search all subdirectories under the D:\java\binaries\jdk\x64\jdk-17.0.7+7\ directory for program files.
• /s specifies the directories containing symbols and multiple directories should be separated with semicolons

Here’s the tail end of the SymChk output:

...
SYMCHK: api-ms-win-crt-utility-l1-1-0.dll FAILED  - api-ms-win-crt-utility-l1-1-0.pdb mismatched or not found
SYMCHK: msvcp140.dll         FAILED  - msvcp140.amd64.pdb mismatched or not found
SYMCHK: ucrtbase.dll         FAILED  - ucrtbase.pdb mismatched or not found
SYMCHK: vcruntime140.dll     FAILED  - vcruntime140.amd64.pdb mismatched or not found
SYMCHK: vcruntime140_1.dll   FAILED  - vcruntime140_1.amd64.pdb mismatched or not found

SYMCHK: FAILED files = 46
SYMCHK: PASSED + IGNORED files = 440

The components that have failures are binaries that are external dependencies of the OpenJDK. Those failures can therefore be safely ignored. An interesting thing to note is that java.dll and java.exe are in the same folder in the OpenJDK installation. Since their symbol files are both called java.pdb, the symbols for java.exe are placed in a subdirectory called exe. This applies to other binaries with similar PDB filename conflicts. See the Symbol Path Syntax section for more details.

The symbols provided also come with .map files. The .map vs pdb search reveals some interesting tidbits about .map files, e.g. that they are an older technology than PDB files, which superseded them (Build Time Improvement Recommendation: Turn off /MAP, use PDBs – C++ Team Blog) and they can be created from PDB files (windows – How to create a .MAP file from a .PDB file – Stack Overflow). See debugging – Why should we need the map file when pdb file is available in windows platform? – Stack Overflow also.