stdlib: Move setting of checkpoints to set_workload funcs

It never made much sense to set checkpoint via the Simulator module as
Checkpoints are very tightly coupled with the Workload being run. This
change therefore moves the checkpoint to the set_workload functions.

Setting checkpoints via the Simulator is deprecated and will be removed
in a future release.

Change-Id: I24d2133b38a86423d3553ec888c917c5fe47b93d
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/64571
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>

src/python/gem5/components/boards/abstract_board.py

@@ -100,6 +100,11 @@ class AbstractBoard:
         # determined by which kind of workload is set.
         self._is_fs = None
 
+        # This variable is used to record the checkpoint directory which is
+        # set when declaring the board's workload and then used by the
+        # Simulator module.
+        self._checkpoint = None
+
         # Setup the board and memory system's memory ranges.
         self._setup_memory_ranges()
 

src/python/gem5/components/boards/kernel_disk_workload.py

@@ -29,8 +29,9 @@ from abc import abstractmethod
 from .abstract_board import AbstractBoard
 from ...resources.resource import AbstractResource
 
-from typing import List, Optional
+from typing import List, Optional, Union
 import os
+from pathlib import Path
 
 import m5
 
@@ -140,6 +141,7 @@ class KernelDiskWorkload:
         readfile_contents: Optional[str] = None,
         kernel_args: Optional[List[str]] = None,
         exit_on_work_items: bool = True,
+        checkpoint: Optional[Union[Path, AbstractResource]] = None,
     ) -> None:
         """
         This function allows the setting of a full-system run with a Kernel
@@ -159,6 +161,8 @@ class KernelDiskWorkload:
         passed to the kernel. By default set to `get_default_kernel_args()`.
         :param exit_on_work_items: Whether the simulation should exit on work
         items. True by default.
+        :param checkpoint: The checkpoint directory. Used to restore the
+        simulation to that checkpoint.
         """
 
         # We assume this this is in a multiple-inheritance setup with an
@@ -202,3 +206,17 @@ class KernelDiskWorkload:
 
         # Set whether to exit on work items.
         self.exit_on_work_items = exit_on_work_items
+
+        # Here we set `self._checkpoint_dir`. This is then used by the
+        # Simulator module to setup checkpoints.
+        if checkpoint:
+            if isinstance(checkpoint, Path):
+                self._checkpoint = checkpoint
+            elif isinstance(checkpoint, AbstractResource):
+                self._checkpoint = Path(checkpoint.get_local_path())
+            else:
+                # The checkpoint_dir must be None, Path, Or AbstractResource.
+                raise Exception(
+                    "Checkpoints must be passed as a Path or an "
+                    "AbstractResource."
+                )

src/python/gem5/components/boards/se_binary_workload.py

@@ -57,6 +57,7 @@ class SEBinaryWorkload:
         stdout_file: Optional[Path] = None,
         stderr_file: Optional[Path] = None,
         arguments: List[str] = [],
+        checkpoint: Optional[Union[Path, AbstractResource]] = None,
     ) -> None:
         """Set up the system to run a specific binary.
 
@@ -70,6 +71,8 @@ class SEBinaryWorkload:
         items. True by default.
         :param stdin_file: The input file for the binary
         :param arguments: The input arguments for the binary
+        :param checkpoint: The checkpoint directory. Used to restore the
+        simulation to that checkpoint.
         """
 
         # We assume this this is in a multiple-inheritance setup with an
@@ -99,11 +102,25 @@ class SEBinaryWorkload:
         # Set whether to exit on work items for the se_workload
         self.exit_on_work_items = exit_on_work_items
 
+        # Here we set `self._checkpoint_dir`. This is then used by the
+        # Simulator module to setup checkpoints.
+        if checkpoint:
+            if isinstance(checkpoint, Path):
+                self._checkpoint = checkpoint
+            elif isinstance(checkpoint, AbstractResource):
+                self._checkpoint_dir = Path(checkpoint.get_local_path())
+            else:
+                raise Exception(
+                    "The checkpoint_dir must be None, Path, or "
+                    "AbstractResource."
+                )
+
     def set_se_simpoint_workload(
         self,
         binary: AbstractResource,
         arguments: List[str] = [],
         simpoint: Union[AbstractResource, SimPoint] = None,
+        checkpoint: Optional[Union[Path, AbstractResource]] = None,
     ) -> None:
         """Set up the system to run a SimPoint workload.
 
@@ -119,6 +136,8 @@ class SEBinaryWorkload:
         :param simpoint: The SimPoint object or Resource that contains the list of
         SimPoints starting instructions, the list of weights, and the SimPoints
         interval
+        :param checkpoint: The checkpoint directory. Used to restore the
+        simulation to that checkpoint.
         """
 
         # convert input to SimPoint if necessary
@@ -139,6 +158,7 @@ class SEBinaryWorkload:
         self.set_se_binary_workload(
             binary=binary,
             arguments=arguments,
+            checkpoint=checkpoint,
         )
 
     def get_simpoint(self) -> SimPoint:

src/python/gem5/simulate/simulator.py

@@ -109,7 +109,9 @@ class Simulator:
         events is valid.
         :param checkpoint_path: An optional parameter specifying the directory
         of the checkpoint to instantiate from. When the path is None, no
-        checkpoint will be loaded. By default, the path is None.
+        checkpoint will be loaded. By default, the path is None. **This
+        parameter is deprecated. Please set the checkpoint when setting the
+        board's workload**.
 
         `on_exit_event` usage notes
         ---------------------------
@@ -222,6 +224,16 @@ class Simulator:
         self._last_exit_event = None
         self._exit_event_count = 0
 
+        if checkpoint_path:
+            warn(
+                "Setting the checkpoint path via the Simulator constructor is "
+                "deprecated and will be removed in future releases of gem5. "
+                "Please set this through via the appropriate workload "
+                "function (i.e., `set_se_binary_workload` or "
+                "`set_kernel_disk_workload`). If both are set the workload "
+                "function set takes precedence."
+            )
+
         self._checkpoint_path = checkpoint_path
 
     def schedule_simpoint(
@@ -402,7 +414,10 @@ class Simulator:
             # m5.instantiate() takes a parameter specifying the path to the
             # checkpoint directory. If the parameter is None, no checkpoint
             # will be restored.
-            m5.instantiate(self._checkpoint_path)
+            if self._board._checkpoint:
+                m5.instantiate(self._board._checkpoint.as_posix())
+            else:
+                m5.instantiate(self._checkpoint_path)
             self._instantiated = True
 
             # Let the board know that instantiate has been called so it can do