dcbaf9f41b
Summary: Boot sequence around apexd is changed to make it possible for pre-apexd processes to use libraries from APEXes. They no longer need to wait for the apexd to finish activating APEXes, which again can be done only after /data/ is mounted. This improves overall boot performance. Detail: This change fixes the problem that processes that are started before apexd (so called pre-apexd processes) can't access libraries that are provided only by the APEXes but are not found in the system partition (e.g. libdexfile_external.so, etc.). Main idea is to activate system APEXes (/system/apex/*.apex) before /data is mounted and then activate the updated APEXes (/data/apex/*.apex) after the /data mount. Detailed boot sequence is as follows. 1) init prepares the bootstrap and default mount namespaces. A tmpfs is mounted on /apex and the propagation type of the mountpoint is set to private. 2) before any other process is started, apexd is started in bootstrap mode. When executed in the mode, apexd only activates APEXes under /system/apex. Note that APEXes activated in this phase are mounted in the bootstrap mount namespace only. 3) other pre-apexd processes are started. They are in the bootstrap mount namespace and thus are provided with the libraries from the system APEXes. 4) /data is mounted. init switches into the default mount namespace and starts apexd as a daemon as usual. 5) apexd scans both /data/apex and /system/apex, and activate latest APEXes from the directories. Note that APEXes activated in this phase are mounted in the default namespaces only and thus are not visible to the pre-apexd processes. Bug: 125549215 Test: m; device boots Change-Id: I21c60d0ebe188fa4f24d6e6861f85ca204843069
28 lines
861 B
C++
28 lines
861 B
C++
/*
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* Copyright (C) 2019 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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namespace android {
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namespace init {
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bool SetupMountNamespaces();
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bool SetupRuntimeBionic();
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bool SwitchToDefaultMountNamespace();
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bool SwitchToBootstrapMountNamespaceIfNeeded();
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} // namespace init
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} // namespace android
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