build_sdk.py: enable building kernels with domains

This commit adds two additional command line arguments to
build_sdk.py:

    --experimental-num-domains: the number of kernel domains;
    --experimental-domain-schedule: path to a C file with the domain
    schedule configuration.

These flags must be used together; neither makes sense on its
own. When these flags are provided, build_sdk.py will build all kernel
images with domains enabled and with the provided configuration. The
flags correspond to the kernel build flags "KernelNumDomains" and
"KernelDomainSchedule", respectively.

All kernels contained in the SDK will have this domain
configuration. There is no way to have some kernels have the domain
configuration and others not, or to have different kernels with
different domain configurations.

These flags are intended as a stopgap solution until the kernel allows
configuration of the domain schedule at runtime. Once that is enabled
in mainline seL4, these flags can be removed from Microkit.

Signed-off-by: James Archer <[email protected]>

build_sdk.py

@@ -428,6 +428,8 @@ def main() -> None:
     parser.add_argument("--skip-tool", action="store_true", help="Tool will not be built")
     parser.add_argument("--skip-docs", action="store_true", help="Docs will not be built")
     parser.add_argument("--skip-tar", action="store_true", help="SDK and source tarballs will not be built")
+    parser.add_argument("--experimental-num-domains", type=int, help="[EXPERIMENTAL] Number of kernel domains")
+    parser.add_argument("--experimental-domain-schedule", type=Path, help="[EXPERIMENTAL] Path to C file specifying kernel domain schedule")
 
     args = parser.parse_args()
 
@@ -451,6 +453,15 @@ def main() -> None:
     else:
         selected_configs = SUPPORTED_CONFIGS
 
+    if args.experimental_num_domains is not None:
+        if args.experimental_domain_schedule is None:
+            raise Exception("User must specify --experimental-domain-schedule when specifying --experimental-num-domains")
+        for config in selected_configs:
+            config.kernel_options["KernelNumDomains"] = str(args.experimental_num_domains)
+            config.kernel_options["KernelDomainSchedule"] = args.experimental_domain_schedule
+    elif args.experimental_domain_schedule is not None:
+        raise Exception("User must specify --experimental-num-domains when specifying --experimental-domain-schedule")
+
     sel4_dir = args.sel4.expanduser()
     if not sel4_dir.exists():
         raise Exception(f"sel4_dir: {sel4_dir} does not exist")