ML and ML64 command-line reference

Assembles and links one or more assembly-language source files. The command-line options are case-sensitive.

For more information on ml64.exe, see MASM for x64 (ml64.exe).

Syntax

ML [options] filename [ [options] filename]

ML64 [options] filename [ [options] filename] ... [/link link_options]

Parameters

options
The options listed in the following table:

Option	Action
/AT	Enables tiny-memory-model support. Enables error messages for code constructs that violate the requirements for .com format files. This option isn't equivalent to the .MODEL TINY directive. Not available in ml64.exe.
/Bl filename	Selects an alternate linker in filename.
/c	Assembles only. Does no linking.
/coff	Generates common object file format (COFF) type of object module. Required for Win32 assembly language development. Not available in ml64.exe.
/Cp	Preserves case of all user identifiers.
/Cu	Maps all identifiers to upper case (default). Not available in ml64.exe.
/Cx	Preserves case in public and extern symbols.
/D symbol⟦=value⟧	Defines a text macro with the given name symbol. If value is missing, it's blank. Multiple tokens separated by spaces must be enclosed in quotation marks.
/EP	Generates a preprocessed source listing (sent to STDOUT). See /Sf.
/ERRORREPORT [ NONE | PROMPT | QUEUE | SEND ]	Deprecated. Error reporting is controlled by Windows Error Reporting (WER) settings.
/F hexnum	Sets stack size to hexnum bytes (the same as /link /STACK:<number>). The value must be expressed in hexadecimal notation. There must be a space between /F and hexnum.
/Fe filename	Names the executable file.
/Fl⟦filename⟧	Generates an assembled code listing. See /Sf.
/Fm⟦filename⟧	Creates a linker map file.
/Fo filename	Names an object file. For more information, see Remarks.
/FPi	Generates emulator fix-ups for floating-point arithmetic (mixed language only). Not available in ml64.exe.
/Fr⟦filename⟧	Generates a source browser .sbr file.
/FR⟦filename⟧	Generates an extended form of a source browser .sbr file.
/Gc	Specifies use of FORTRAN- or Pascal-style conventions for function calls and names. Same as OPTION LANGUAGE:PASCAL. Not available in ml64.exe.
/Gd	Specifies use of C-style conventions for function calls and names. Same as OPTION LANGUAGE:C. Not available in ml64.exe.
/Gz	Specifies use of __stdcall conventions for function calls and names. Same as OPTION LANGUAGE:STDCALL. Not available in ml64.exe.
/H number	Restricts external names to number significant characters. The default is 31 characters. Not available in ml64.exe.
/help	Displays a summary of ML command-line syntax and options.
/I pathname	Sets path for include file. A maximum of 10 /I options is allowed.
/nologo	Suppresses messages for successful assembly.
/omf	Generates object module file format (OMF) type of object module. /omf implies /c. ML.exe doesn't support linking OMF objects. Not available in ml64.exe.
/quiet	Suppresses 'Assembling' message. Available in Visual Studio 17.6 and later.
/Sa	Turns on listing of all available information.
/safeseh	Marks the object file: either it contains no exception handlers, or it contains exception handlers that are all declared with .SAFESEH. Not available in ml64.exe.
/Sf	Adds the first-pass listing to the listing file.
/Sl width	Sets the line width of source listing in characters per line to width. Range is 60-255 or 0. Default is 0. Same as PAGE width.
/Sn	Turns off symbol table when a listing is produced.
/Sp length	Sets the page length of source listing in lines per page to length. Range is 10-255 or 0. Default is 0. Same as PAGE length.
/Ss text	Specifies text for source listing. Same as SUBTITLE text.
/St text	Specifies title for source listing. Same as TITLE text.
/Sx	Turns on false conditionals in listing.
/Ta filename	Assembles source file whose name doesn't end with the .asm extension.
/w	Same as /W0 /WX.
/W level	Sets the warning level, where level = 0, 1, 2, or 3.
/WX	If warnings are generated, returns an error code.
/X	Ignore INCLUDE environment path.
/Zd	Generates line-number information in object file.
/Zf	Makes all symbols public.
/ZH:MD5	Use MD5 for checksum in debug info.
/ZH:SHA_256	Use SHA256 for checksum in debug info (default in Visual Studio 2022 version 17.0 and later).
/Zi	Generates CodeView information in object file.
/Zm	Enables M510 option for maximum compatibility with MASM 5.1. Not available in ml64.exe.
/Zp⟦alignment⟧	Packs structures on the specified byte boundary. The alignment can be 1, 2, 4, 8, or 16.
/Zs	Performs a syntax check only.
/?	Displays a summary of ML command-line syntax and options.

filename
The name of the file.

link_options
The link options. For more information, see Linker options.

Remarks

Some command-line options to ML and ML64 are placement-sensitive. For example, because ML and ML64 can accept several /c options, any corresponding /Fo options must be specified before /c. The following command-line example illustrates an object file specification for each assembly file specification:

ml.exe /Fo a1.obj /c a.asm /Fo b1.obj /c b.asm

Environment Variables

Variable	Description
INCLUDE	Specifies search path for include files.
ML	Specifies default command-line options.
TMP	Specifies path for temporary files.

See also

ML error messages
Microsoft Macro Assembler reference