The nature of hot reload in libxposed API 102?

[victay44]

Per this commit's description, a module that hooks system_server should no longer requires a reboot.
I wonder if this only applies to a module that already hooked into and started with system_server, so updating it won't necessitate a reboot. Or a new module can seamlessly hooks into system_server as well? Would it work also with DISABLING a module that hooks system_server?

In my test a new module won't be active until I reboot, but Idk if that's the intended behavior or if the hot reload doesn't do its supposed things correctly. My device is lineageOS A15 with Vector 2.2 release build.

[Maxaubert]

Your test matches the intended behavior. Hot reload only replaces the code of a module that is already loaded in a running process. It does not add or remove a module from system_server.

The PR you linked describes it this way: it is "replacing a module's code inside a running process", and a target is a process that already received the module from the daemon (#757). The reload is also only offered to modules that are already loaded in system_server. So:

• Updating a module that is already running in system_server: no reboot needed. Hot reload swaps the code, either when the module calls hotReloadModule() or automatically if it sets autoHotReload=true in module.prop and agrees in onHotReloading().
• A new module, or enabling a module for System Framework for the first time: not covered. system_server asks the daemon for its module list once, while it starts, so a module that was not in that list is never loaded into the process.
• Disabling or removing a module from the System Framework scope: also not covered. A module already loaded stays loaded until system_server restarts.

The manager's scope screen documents this in a comment: "system_server reads its module list once, when it starts ... True for leaving as well as joining – a module already loaded into system_server stays loaded until that process goes." (

Vector/manager/src/main/kotlin/org/matrix/vector/manager/ui/screens/modules/ScopeViewModel.kt

Lines 916 to 924 in efb8288

	// system_server reads its module list once, when it starts:
	// SystemServerService hands the zygisk module whatever
	// ConfigCache.getModulesForSystemServer() holds at that moment. Every
	// other target picks a scope up when its own process next starts, which
	// happens on its own; this one does not until the framework is restarted,
	// so the change is stored and inert and nothing on screen would say so.
	// True for leaving as well as joining — a module already loaded into
	// system_server stays loaded until that process goes.
	if (wasThere != isThere) _frameworkRestartNeeded.value = true

)

After you change the System Framework scope, the manager shows a dialog, "The framework has not picked this up yet" (

Vector/manager/src/main/res/values/strings.xml

Lines 442 to 444 in efb8288

	<string name="scope_framework_restart_title">The framework has not picked this up yet</string>
	<string name="scope_framework_restart_body">System Framework is loaded once, when Android starts it. This change reaches it only when the framework restarts — every running app closes, and the phone itself stays on.</string>
	<string name="scope_framework_restart_later">Later</string>

). It offers a soft reboot, which restarts the zygote and system_server without rebooting the phone. Tap that, or use the "Soft reboot" action in the manager, instead of a full reboot. The new module is then loaded on the way up.