commit | db11d759b127f43f60d179ecb90af501bc11e578 | [log] [tgz] |
---|---|---|
author | Jooyung Han <jooyung@google.com> | Mon Dec 19 14:52:07 2022 +0900 |
committer | Jooyung Han <jooyung@google.com> | Mon Dec 19 14:55:02 2022 +0900 |
tree | 7ac08a881f2aa70826d398599e7d9c6f175bb8b8 | |
parent | 2f63b63e60b618909e927dac56aada3f5f879eb6 [diff] |
Use shared libc++ on device The runtime apex already has artifacts depending on libc++.so. So, on device, using shared libc++.so can save us some storage. (On aosp_cf_x86_64_phone-userdebug, it's reduced 662944->450632, which affects the sizes of runtime and virt apexes.) However, on host, linkerconfig is statically linked with libc++ for convenience. (No extra setup needed to run linkerconfig on host for libc++.so). Bug: 262330207 Test: m && boot Change-Id: I47b9192cfe6142f327a4eb1a160b751a887420d6
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.