[PATCH v11 4/5] Documentation/kbuild: Document storage of symbol information
From: Matthew Maurer <hidden>
Date: 2024-12-23 20:13:41
Also in:
linux-doc, linux-kbuild, linux-modules, lkml, rust-for-linux
Subsystem:
documentation, kernel build + files below scripts/ (unless maintained elsewhere), the rest · Maintainers:
Jonathan Corbet, Nathan Chancellor, Nicolas Schier, Linus Torvalds
Document where exported and imported symbols are kept, format options, and limitations. Signed-off-by: Matthew Maurer <redacted> --- Documentation/kbuild/modules.rst | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+)
diff --git a/Documentation/kbuild/modules.rst b/Documentation/kbuild/modules.rst
index 101de236cd0c9abe1f5684d80063ff3f9a7fc673..a42f00d8cb90ff6ee44677c1278287ef25a84c89 100644
--- a/Documentation/kbuild/modules.rst
+++ b/Documentation/kbuild/modules.rst@@ -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 ----------------------------
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