@@ -13,3 +13,4 @@ are only implementing things for HW accelerated hypervisors.
multi-thread-tcg
tcg-icount
tcg-plugins
+ replay
new file mode 100644
@@ -0,0 +1,54 @@
+..
+ Copyright (c) 2022, ISP RAS
+ Written by Pavel Dovgalyuk
+
+=======================
+Execution Record/Replay
+=======================
+
+Record/replay mechanism, that could be enabled through icount mode, expects
+the virtual devices to satisfy the following requirements.
+
+The main idea behind this document is that everything that affects
+the guest state during execution in icount mode should be deterministic.
+
+Timers
+------
+
+All virtual devices should use virtual clock for timers that change the guest
+state. Virtual clock is deterministic, therefore such timers are deterministic
+too.
+
+Virtual devices can also use realtime clock for the events that do not change
+the guest state directly. When the clock ticking should depend on VM execution
+speed, use virtual clock with EXTERNAL attribute. It is not deterministic,
+but its speed depends on the guest execution. This clock is used by
+the virtual devices (e.g., slirp routing device) that lie outside the
+replayed guest.
+
+Bottom halves
+-------------
+
+Bottom half callbacks, that affect the guest state, should be invoked through
+replay_bh_schedule_event or replay_bh_schedule_oneshot_event functions.
+Their invocations are saved in record mode and synchronized with the existing
+log in replay mode.
+
+Saving/restoring the VM state
+-----------------------------
+
+All fields in the device state structure (including virtual timers)
+should be restored by loadvm to the same values they had before savevm.
+
+Avoid accessing other devices' state, because the order of saving/restoring
+is not defined. It means that you should not call functions like
+'update_irq' in post_load callback. Save everything explicitly to avoid
+the dependencies that may make restoring the VM state non-deterministic.
+
+Stopping the VM
+---------------
+
+Stopping the guest should not interfere with its state (with the exception
+of the network connections, that could be broken by the remote timeouts).
+VM can be stopped at any moment of replay by the user. Restarting the VM
+after that stop should not break the replay by the unneeded guest state change.
deleted file mode 100644
@@ -1,46 +0,0 @@
-Record/replay mechanism, that could be enabled through icount mode, expects
-the virtual devices to satisfy the following requirements.
-
-The main idea behind this document is that everything that affects
-the guest state during execution in icount mode should be deterministic.
-
-Timers
-======
-
-All virtual devices should use virtual clock for timers that change the guest
-state. Virtual clock is deterministic, therefore such timers are deterministic
-too.
-
-Virtual devices can also use realtime clock for the events that do not change
-the guest state directly. When the clock ticking should depend on VM execution
-speed, use virtual clock with EXTERNAL attribute. It is not deterministic,
-but its speed depends on the guest execution. This clock is used by
-the virtual devices (e.g., slirp routing device) that lie outside the
-replayed guest.
-
-Bottom halves
-=============
-
-Bottom half callbacks, that affect the guest state, should be invoked through
-replay_bh_schedule_event or replay_bh_schedule_oneshot_event functions.
-Their invocations are saved in record mode and synchronized with the existing
-log in replay mode.
-
-Saving/restoring the VM state
-=============================
-
-All fields in the device state structure (including virtual timers)
-should be restored by loadvm to the same values they had before savevm.
-
-Avoid accessing other devices' state, because the order of saving/restoring
-is not defined. It means that you should not call functions like
-'update_irq' in post_load callback. Save everything explicitly to avoid
-the dependencies that may make restoring the VM state non-deterministic.
-
-Stopping the VM
-===============
-
-Stopping the guest should not interfere with its state (with the exception
-of the network connections, that could be broken by the remote timeouts).
-VM can be stopped at any moment of replay by the user. Restarting the VM
-after that stop should not break the replay by the unneeded guest state change.