| commit | 339ad9d32652c501c762aab75ebe8dcca73fd33f | [log] [tgz] |
|---|---|---|
| author | Chan Wang <chanwang@google.com> | Mon Nov 11 14:07:21 2024 +0000 |
| committer | Chan Wang <chanwang@google.com> | Tue Nov 12 10:57:14 2024 +0000 |
| tree | adaabc528f06576385ce1272c7ffb0416c5d2892 | |
| parent | e65185d0ea9be7b32d27eea05838473533b6078f [diff] |
Use 'partition' instead of 'preinstalledModulePath' field in 'ApexInfo' to decide apex partition Bug: 3335753 Test: atest linkerconfig_modules_unittest Test: atest linkerconfig_backward_compatibility_test Test: atest linkerconfig_generator_unittest Test: atest linkerconfig_contents_fulltest Test: atest linkerconfig_diff_test Change-Id: I35d1d40980fac03dd4d5d7572ddd0d50c5c815e9
Linkerconfig is a program to generate linker configuration based on the runtime environment. Linkerconfig generates one or more ld.config.txt files and some other files under /linkerconfig during init. Linker will read this generated configuration file(s) to find out link relationship between libraries and executable.
TODO: explain inputs (e.g. /system/etc/public.libraries.txt, /apex/apex-info-list.xml, ..)
Linker configuration file can be used to add extra information while linkerconfig creates linker configuration with the module. This module can be defined as linker_config from Soong, and it will be translated as protobuf file at build time.
A linker configuration file(linker.config.json) is compiled into a protobuf at build time by conv_linker_config. You can find the compiled file under <base>/etc/linker.config.pb. For example, /apex/com.android.art/etc/linker.config.pb is a configuration for the com.android.art APEX.
/system/etc/linker.config.pb(or its source module system_linker_config) is special because its provideLibs key is generated at build time.
linker.config.json file is in json format which can contain properties as below.
| Property Name | Type | Description | Allowed module |
|---|---|---|---|
| permittedPaths | List | Additional permitted paths | APEX |
| visible | bool | Force APEX namespace to be visible from all sections if the value is true | APEX |
| provideLibs | List | Libraries providing from the module | System |
| requireLibs | List | Libraries required from the module | System |
{
"permittedPaths" : [ "/a", "/b/c", "/d/e/f"],
"visible": true
}
{
"provideLibs" : [ "a.so", "b.so", "c.so" ],
"requireLibs" : [ "foo.so", "bar.so", "baz.so" ]
}
linkerconfig reads both /system/etc/public.libraries.txt and /vendor/etc/public.libraries.txt to identify libraries that are provided by APEX and accessible from apps via libnativeloader.
linkerconfig generates apex.libraries.config.txt file which lists public libraries provided APEX. libnativeloader, then, links those libraries from classloader-namespace to providing APEXes.
TODO: a few words about the files
Check ld.config.format.md.
The file describes libraries exposed from APEXes. libnativeloader is the main consumer of this file.
# comment line jni com_android_foo libfoo_jni.so public com_android_bar libbar.so:libbaz.so
The file is line-based and each line consists of tag apex_namespace library_list.
tag explains what library_list is.apex_namespace is the namespace of the apex. Note that it is mangled like com_android_foo for the APEX(“com.android.foo”).library_list is colon-separated list of library names.tag is jni, library_list is the list of JNI libraries exposed by apex_namespace.tag is public, library_list is the list of public libraries exposed by apex_namespace. Here, public libraries are the libs listed in /system/etc/public.libraries.txt.