The .debug section is used in object files to contain compiler-generated debug information, and in image files to contain the total debug information generated. This section describes the packaging of debug information in object and image files. The actual format of CodeView debug information is not described here. See the document CV4 Symbolic Debug Information Specification.
The next section describes the format of the debug directory, which can be anywhere in the image. Subsequent sections describe the "groups" in object files that contain debug information.
The default for the linker is that debug information is not mapped into the address space of the image. A .debug section exists only when debug information is mapped in the address space.