GFlags Overview

GFlags (gflags.exe), the Global Flags Editor, enables and disables advanced internal system diagnostic and troubleshooting features. You can run GFlags from a Command Prompt window or use its graphical user interface dialog box.

Use GFlags to activate the following features:

Registry

Set system-wide debugging features for all processes running on the computer. These settings are stored in the GlobalFlag registry entry (HKEY_LOCAL_MACHINE\ SYSTEM\ CurrentControlSet\ Control\ Session Manager\ GlobalFlag). They take effect when you restart Windows and remain effective until you change them and restart again.

Kernel flag settings

Set debugging features for this session. These settings are effective immediately, but are lost when Windows shuts down. The settings affect all processes started after this command completes.

Image file settings

Set debugging features for a particular program. These settings are stored in a GlobalFlag registry entry for each program (HKEY_LOCAL_MACHINE\ SOFTWARE\ Microsoft\ Windows NT\ CurrentVersion\ Image File Execution Options\ ImageFileName\ GlobalFlag). They take effect when you restart the program and remain effective until you change them.

Debugger

Specify that a particular program always runs in a debugger. This setting is stored in the registry. It is effective immediately and remains effective until you change it. (This feature is available only in the Global Flags dialog box.)

Launch

Run a program with the specified debugging settings. The debugging settings are effective until the program stops. (This feature is available only from the Global Flags dialog box.)

Special Pool

Request that allocation with a specified pool tag or of a specified size are filled from the special pool. This feature helps you to detect and identify the source of errors in kernel pool use, such as writing beyond the allocated memory space, or referring to memory that has already been freed.

Beginning in Windows Vista, you can enable, disable, and configure the special pool feature (Kernel Special Pool Tag) as a kernel flags setting, which does not require a reboot, or as a registry setting, which requires a reboot.

Page heap verification

Enable, disable, and configure page heap verification for a program. When enabled, page heap monitors dynamic heap memory operations, including allocation and free operations, and causes a debugger break when it detects a heap error.