swapadd

A small native Windows command-line utility for displaying active paging files or creating an additional paging file in the running system.

Usage

Run without arguments to display paging-file names, sizes, current usage, and peak usage, followed by physical-memory, registry-quota, and paged-pool information:

swapadd

To request a new paging file:

swapadd filename minsize[K|M|G] maxsize[K|M|G]

For example, from an elevated command prompt:

swapadd C:\additional-pagefile.sys 256M 1G

This requests an initial/minimum size of 256 MiB and a maximum size of 1 GiB. Unsuffixed sizes are bytes; uppercase K, M, and G multiply by powers of 1024. Use positive sizes with the minimum no larger than the maximum, and choose a volume with enough free space.

Creation requires the Create a pagefile privilege (SeCreatePagefilePrivilege). The tool attempts to enable it in the process token before calling NtCreatePagingFile; elevation alone cannot grant a privilege absent from that token.

Successful creation prints OK.. The tool changes the running system and does not write persistent paging-file configuration to the registry. Configure paging files separately in Windows if they should be created again at subsequent boots. There is no command to remove a paging file.

Query and creation failures are reported to standard error and returned as translated Windows error codes. Invalid argument counts or size syntax display usage and return a nonzero exit code.

Build

The repository contains swapadd.cpp and a legacy Microsoft NMake makefile. It requires a Windows C++ build environment with cl, link, and nmake, Windows headers/import libraries, and the shared LTRData dependencies:

• Headers from LTRData/include, including ntdll.h, winstrct.h, and winstrct.hpp. The makefile expects the checkout at ../include; add that directory to the compiler's include search path.
• Matching-architecture winstrct.lib and winstrcp.lib on the linker search path. These are requested by the shared headers; related support sources are in LTRData/libsrc.
• ../lib/minwcrt.lib, which the makefile lists as a prerequisite even though it does not pass it explicitly to the linker.

After arranging those dependencies, an example from an x64 compiler command prompt is:

mkdir amd64
nmake CPU=amd64

The output is amd64/swapadd.exe. The CPU value selects the output directory and makefile options; it does not select a compiler toolchain. Create the output directory before building. Without an explicit CPU, the makefile uses _BUILDARCH if set, otherwise i386.

The repository retains its original 2021 source and legacy build setup, with no automated build or test configuration.

License

MIT License, copyright Olof Lagerkvist.