commit | 2f63b63e60b618909e927dac56aada3f5f879eb6 | [log] [tgz] |
---|---|---|
author | Jooyung Han <jooyung@google.com> | Tue Dec 13 17:59:48 2022 +0900 |
committer | Jooyung Han <jooyung@google.com> | Wed Dec 14 13:50:12 2022 +0900 |
tree | 70a186995866f9d660d19894535b27eb482c5180 | |
parent | 0c39839332b493bf2f95295b3a42b806de24809b [diff] |
Make linkerconfig non-static linkerconfig doesn't need to be static. Being dynamic, the size is 50% smaller than before. It was static because it's linkerconfig itself that generates ld.config.txt. But since linker provides the default linker config which is suitable for linkerconfig, it can be dynamically linked without ld.config.txt. Bug: 262330207 Bug: 260982509 Test: MicrodroidAppTest Test: device boots Change-Id: I0e36039cf99ca6dcc0913a0ec6b16b5e7c2c7abf
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" ] }
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.