serialize the ABI of an ELF file abidw reads a shared library in ELF format and emits an XML representation of its ABI to standard output. The emitted representation format, named ABIXML, includes …
abidw [options] [<path-to-elf-file>]
This is a debugging and sanity check option.
Display the version of the ABIXML format emitted by this program and exit.
For each of the comma-separated binaries given in argument to this option, if the binary is found in the directory specified by the –added-binaries-dir option, then load the ABI corpus of the binary and add it to a set of ABI corpora (called a ABI Corpus Group) made of the binary denoted by the Argument of abidw. That corpus group is then serialized out.
This option is to be used in conjunction with the --add-binaries, the --follow-dependencies or the --list-dependencies option. Binaries listed as arguments of the --add-binaries option or being dependencies of the input binary in the case of the --follow-dependencies option and found in the directory <dir-path> are going to be loaded as ABI corpus and added to the set of ABI corpora (called an ABI corpus group) built and serialized.
When looking at the debug information accompanying a binary, this tool analyzes the descriptions of the types reachable by the interfaces (functions and variables) that are visible outside of their translation unit. Once that analysis is done, an ABI corpus is constructed by only considering the subset of types reachable from interfaces associated to ELF symbols that are defined and exported by the binary. It’s that final ABI corpus which textual representation is saved as ABIXML.
The problem with that approach however is that analyzing all the interfaces that are visible from outside their translation unit can amount to a lot of data, especially when those binaries are applications, as opposed to shared libraries. One example of such applications is the Linux Kernel. Analyzing massive ABI corpora like these can be extremely slow.
In the presence of an “average sized” binary however one can afford having libabigail analyze all interfaces that are visible outside of their translation unit, using this option.
Note that this option is turned on by default, unless we are in the presence of the Linux Kernel.
Extract ABI information from BTF debug information, if present in the given object.
If the debug info for the file elf-path contains a reference to an alternate debug info file, abidw checks that it can find that alternate debug info file. In that case, it emits a meaningful success message mentioning the full path to the alternate debug info file found. Otherwise, it emits an error code.
Like --check-alternate-debug-info, but in the success message, only mention the base name of the debug info file; not its full path.
This is an optional debugging and sanity check option. To enable it the libabigail package needs to be configured with the –enable-debug-self-comparison option.
Extract ABI information from CTF debug information, if present in the given object.
In cases where the debug info for path-to-elf-file is in a separate file that is located in a non-standard place, this tells abidw where to look for that debug info file.
Note that dir-path must point to the root directory under which the debug information is arranged in a tree-like manner. Under Red Hat based systems, that directory is usually <root>/usr/lib/debug.
This option can be provided several times with different root directories. In that case, abidw will potentially look into all those root directories to find the split debug info for the elf file.
Note that this option is not mandatory for split debug information installed by your system’s package manager because then abidw knows where to find it.
This option is available only if the package was configured with the –enable-debug-type-canonicalization option.
This option is implicitly set by option –headers-dir and –header-file options.
With this option, types that are NOT defined in the headers are entirely dropped from the internal representation build by Libabigail to represent the ABI and will not end up in the abi XML file.
This option is provided or compatibility reasons only and should not be explicitly used anymore.
With this option functions or variables for which the (exported) ELF symbol is undefined are dropped from the internal representation build by Libabigail to represent the ABI and will not end up in the abi XML file.
By default, when looking at the debug information accompanying a binary, this tool analyzes the descriptions of the types reachable by the interfaces (functions and variables) that are visible outside of their translation unit. Once that analysis is done, an ABI corpus is constructed by only considering the subset of types reachable from interfaces associated to ELF symbols that are defined and exported by the binary. It’s that final ABI corpus which textual representation is saved as ABIXML.
The problem with that approach however is that analyzing all the interfaces that are visible from outside their translation unit can amount to a lot of data, especially when those binaries are applications, as opposed to shared libraries. One example of such applications is the Linux Kernel. Analyzing massive ABI corpora like these can be extremely slow.
To mitigate that performance issue, this option allows libabigail to only analyze types that are reachable from interfaces associated with defined and exported ELF symbols.
Note that this option is turned on by default when analyzing the Linux Kernel. Otherwise, it’s turned off by default.
For each dependency of the input binary of abidw, if it is found in the directory specified by the --added-binaries-dir option, then construct an ABI corpus out of the dependency and add it to a set of ABI corpora (called an ABI Corpus Group) along with the ABI corpus of the input binary of the program. The ABI Corpus Group is then serialized out.
This option must be used alongside option –suppression.
It forces suppression specifications to be applied in early suppression mode. Artifacts of the internal representation that are matched by suppression specifications are thus suppressed from memory.
If this option is not used then only suppression specifications with the drop property set to ‘yes’ are effective. All other suppression specification directives will appear to be ignored.
Specifies where to find the public headers of the binary that the tool has to consider. The tool will thus filter out types that are not defined in public headers. This option implicitly sets option –drop-private-types.
Note that several public header directories can be specified for the binary to consider. In that case the --header-dir option should be present several times on the command line, like in the following example:
$ abidw --header-dir /some/path \
--header-dir /some/other/path \
binary > binary.abi
Specifies where to find one of the public headers of the abi file that the tool has to consider. The tool will thus filter out types that are not defined in public headers.
This option implicitly sets option –drop-private-types.
Display a short help about the command and exit.
When analyzing a Linux Kernel binary, this option points to the list of names of ELF symbols of functions and variables which ABI must be written out. Any function or variable with a name that is not included in that list will not ignored. That list is called a “ Kernel Module Interface stable list”. This is because for the Kernel, we don’t talk about the ABI; we rather talk about the interface between the Kernel and its module. Hence the term KMI rather than KABI.
Any other function or variable which ELF symbol are not present in that stable list will not be considered by the KMI writing process.
If this option is not provided – thus if no stable list is provided – then the entire KMI, that is, all publicly defined and exported functions and global variables by the Linux Kernel binaries is emitted.
For each dependency of the input binary of``abidw``, if it’s found in the directory specified by the --added-binaries-dir option, then the name of the dependency is printed out.
By default, libabigail (and thus abidw) only loads types that are reachable from functions and variables declarations that are publicly defined and exported by the binary. So only those types are present in the output of abidw. This option however makes abidw load all the types defined in the binaries, even those that are not reachable from public declarations.
Make abidw to consider the input path as a path to a directory containing the vmlinux binary as several kernel modules binaries. In that case, this program emits the representation of the Kernel Module Interface (KMI) on the standard output.
Below is an example of usage of abidw on a Linux Kernel tree.
First, checkout a Linux Kernel source tree and build it. Then install the kernel modules in a directory somewhere. Copy the vmlinux binary into that directory too. And then serialize the KMI of that kernel to disk, using abidw:
$ git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git $ cd linux && git checkout v4.5 $ make allyesconfig all $ mkdir build-output $ make INSTALL_MOD_PATH=./build-output modules_install $ cp vmlinux build-output/modules/4.5.0 $ abidw --linux-tree build-output/modules/4.5.0 > build-output/linux-4.5.0.kmi
When analysing a binary originating from C++ code using DWARF debug information, libabigail assumes the One Definition Rule to speed-up the analysis. In that case, when several types have the same name in the binary, they are assumed to all be equal.
This option disables that assumption and instructs libabigail to actually actually compare the types to determine if they are equal.
Do not emit the path attribute for the ABI corpus.
Do not include the list of DT_NEEDED dependency names in the corpus.
When analysing a binary which DWARF debug information was processed with the DWZ tool, the type information is supposed to be already factorized. That context is used by libabigail to perform some speed optimizations.
This option disables those optimizations.
By default, libabigail (and thus abidw) loads information about undefined function and variable symbols as well as functions and variables that are associated with those undefined symbols. Those are called undefined interfaces. This option however makes makes abidw avoid loading information about undefined interfaces. The resulting XML file thus doesn’t contain information about those undefined interfaces.
Without this option, if abipkgiff detects that the binaries it is looking at are Linux Kernel binaries (either vmlinux or modules) then it only considers functions and variables which ELF symbols are listed in the __ksymtab and __ksymtab_gpl sections.
With this option, abipkgdiff considers the binary as a non-special ELF binary. It thus considers functions and variables which are defined and exported in the ELF sense.
This option instructs abidw to not emit the XML representation of the ABI. So it only reads the ELF and debug information, builds the internal representation of the ABI and exits. This option is usually useful for debugging purposes.
In the emitted ABI representation, do not show names of function parameters, just the types.
In the XML ABI representation, do not write the size-in-bits for pointer type definitions, reference type definitions, function declarations and function types when they are equal to the default address size of the translation unit. Note that libabigail before 1.8 will not set the default size and will interpret types without a size-in-bits attribute as zero sized.
This option instructs abidw to emit the XML representation of path-to-elf-file into the file file-path, rather than emitting it to its standard output.
Emit statistics about various internal things.
Use a suppression specification file located at path-to-suppression-specifications-file. Note that this option can appear multiple times on the command line. In that case, all of the provided suppression specification files are taken into account. ABI artifacts matched by the suppression specifications are suppressed from the output of this tool.
Only suppression specifications that have the drop property set to ‘yes’ are going to be effective. All other suppression specification directives will appear as being ignored, unless the command line option –force-early-suppression is provided.
This option controls how types are idenfied in the generated XML files. The default sequence style just numbers (with type-id- as prefix) the types in the order they are encountered. The hash style uses a (stable, portable) hash of libabigail’s internal type names and is intended to make the XML files easier to diff.
Emit verbose logs about the progress of miscellaneous internal things.
Display the version of the program and exit.
$ abidw binary > binary.abi
$ abidw --added-binaries=bin1,bin2,bin3 \
--added-binaries-dir /some/where \
binary > binaries.abi
Note that the binaries bin1, bin2 and bin3 are to be found in the directory /some/where. A representation of the ABI of the set of binaries binary, bin1, bin2 and bin3 called an ABI corpus group is serialized in the file binaries.abi.
$ abidw --follow-dependencies \
--added-binaries-dir /some/where \
binary > binary.abi
Note that only the dependencies that are found in the directory /some/where are analysed. Their ABIs, along with the ABI the binary named binary are represented as an ABI corpus group and serialized in the file binary.abi, in the ABIXML format.
As of the version 4 of the DWARF specification, Alternate debug information is a GNU extension to the DWARF specification. It has however been proposed for inclusion into the upcoming version 5 of the DWARF standard. You can read more about the GNU extensions to the DWARF standard here.
Dodji Seketeli
2014-2025, Red Hat, Inc.