Commit 272f8a6d authored by Matthew Maurer's avatar Matthew Maurer Committed by Masahiro Yamada
Browse files

Documentation/kbuild: Document storage of symbol information 



Document where exported and imported symbols are kept, format options,
and limitations.

Signed-off-by: default avatarMatthew Maurer <mmaurer@google.com>
Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
parent e8639b7e

Documentation/kbuild/modules.rst

+20 −0
Original line number Diff line number Diff line
@@ -423,6 +423,26 @@ Symbols From the Kernel (vmlinux + modules) 
	1) It lists all exported symbols from vmlinux and all modules.

	2) It lists the CRC if CONFIG_MODVERSIONS is enabled.



Version Information Formats

---------------------------



	Exported symbols have information stored in __ksymtab or __ksymtab_gpl

	sections. Symbol names and namespaces are stored in __ksymtab_strings,

	using a format similar to the string table used for ELF. If

	CONFIG_MODVERSIONS is enabled, the CRCs corresponding to exported

	symbols will be added to the __kcrctab or __kcrctab_gpl.



	If CONFIG_BASIC_MODVERSIONS is enabled (default with

	CONFIG_MODVERSIONS), imported symbols will have their symbol name and

	CRC stored in the __versions section of the importing module. This

	mode only supports symbols of length up to 64 bytes.



	If CONFIG_EXTENDED_MODVERSIONS is enabled (required to enable both

	CONFIG_MODVERSIONS and CONFIG_RUST at the same time), imported symbols

	will have their symbol name recorded in the __version_ext_names

	section as a series of concatenated, null-terminated strings. CRCs for

	these symbols will be recorded in the __version_ext_crcs section.



Symbols and External Modules

----------------------------