[RFC PATCH] kunit: tool: Enable virtio/PCI by default on UML

[David Gow <davidgow@google.com>]

There are several tests which depend on PCI, and hence need a bunch of
extra options to run under UML. This makes it awkward to give
configuration instructions (whether in documentation, or as part of a
.kunitconfig file), as two separate, incompatible sets of config options
are required for UML and "most other architectures".

For non-UML architectures, it's possible to add default kconfig options
via the qemu_config python files, but there's no equivalent for UML. Add
a new tools/testing/kunit/configs/arch_uml.config file containing extra
kconfig options to use on UML.

Signed-off-by: David Gow <davidgow@google.com>
---

It's really ugly to have to type:
	--kconfig_add CONFIG_VIRTIO_UML=y
	--kconfig_add CONFIG_UML_PCI_OVER_VIRTIO=y
when running many tests under UML, particularly since it isn't required
on other architectures.

This came up in discussion with Daniel this morning, and while the
ability to repeat the --kunitconfig flag would go some way to alleviate
this, having to add:
	--kunitconfig ./tools/testing/kunit/config/uml_pci.kunitconfig
isn't all that much better.

So it seems like adding something by default would be nice.

This implementation is not perfect (in particular, there's no easy way
of _disabling_ these options now, though [1] probably will help). The
'arch_uml.config' filename can be bikeshedded, too.

Thoughts?

---
 tools/testing/kunit/configs/arch_uml.config |  5 +++++
 tools/testing/kunit/kunit_kernel.py         | 11 ++++++++---
 2 files changed, 13 insertions(+), 3 deletions(-)
 create mode 100644 tools/testing/kunit/configs/arch_uml.config

diff --git a/tools/testing/kunit/configs/arch_uml.config b/tools/testing/kunit/configs/arch_uml.config
new file mode 100644
index 000000000000..e824ce43b05a
--- /dev/null
+++ b/tools/testing/kunit/configs/arch_uml.config
@@ -0,0 +1,5 @@
+# Config options which are added to UML builds by default
+
+# Enable virtio/pci, as a lot of tests require it.
+CONFIG_VIRTIO_UML=y
+CONFIG_UML_PCI_OVER_VIRTIO=y
diff --git a/tools/testing/kunit/kunit_kernel.py b/tools/testing/kunit/kunit_kernel.py
index 3539efaf99ba..05e7b1e188d7 100644
--- a/tools/testing/kunit/kunit_kernel.py
+++ b/tools/testing/kunit/kunit_kernel.py
@@ -26,6 +26,7 @@ KUNITCONFIG_PATH = '.kunitconfig'
 OLD_KUNITCONFIG_PATH = 'last_used_kunitconfig'
 DEFAULT_KUNITCONFIG_PATH = 'tools/testing/kunit/configs/default.config'
 BROKEN_ALLCONFIG_PATH = 'tools/testing/kunit/configs/broken_on_uml.config'
+UML_KCONFIG_PATH = 'tools/testing/kunit/configs/arch_uml.config'
 OUTFILE_PATH = 'test.log'
 ABS_TOOL_PATH = os.path.abspath(os.path.dirname(__file__))
 QEMU_CONFIGS_DIR = os.path.join(ABS_TOOL_PATH, 'qemu_configs')
@@ -53,7 +54,7 @@ class LinuxSourceTreeOperations:
 		except subprocess.CalledProcessError as e:
 			raise ConfigError(e.output.decode())
 
-	def make_arch_qemuconfig(self, base_kunitconfig: kunit_config.Kconfig) -> None:
+	def make_arch_config(self, base_kunitconfig: kunit_config.Kconfig) -> None:
 		pass
 
 	def make_allyesconfig(self, build_dir: str, make_options) -> None:
@@ -109,7 +110,7 @@ class LinuxSourceTreeOperationsQemu(LinuxSourceTreeOperations):
 		self._kernel_command_line = qemu_arch_params.kernel_command_line + ' kunit_shutdown=reboot'
 		self._extra_qemu_params = qemu_arch_params.extra_qemu_params
 
-	def make_arch_qemuconfig(self, base_kunitconfig: kunit_config.Kconfig) -> None:
+	def make_arch_config(self, base_kunitconfig: kunit_config.Kconfig) -> None:
 		kconfig = kunit_config.parse_from_string(self._kconfig)
 		base_kunitconfig.merge_in_entries(kconfig)
 
@@ -137,6 +138,10 @@ class LinuxSourceTreeOperationsUml(LinuxSourceTreeOperations):
 	def __init__(self, cross_compile=None):
 		super().__init__(linux_arch='um', cross_compile=cross_compile)
 
+	def make_arch_config(self, base_kunitconfig: kunit_config.Kconfig) -> None:
+		kconfig = kunit_config.parse_file(UML_KCONFIG_PATH)
+		base_kunitconfig.merge_in_entries(kconfig)
+
 	def make_allyesconfig(self, build_dir: str, make_options) -> None:
 		kunit_parser.print_with_timestamp(
 			'Enabling all CONFIGs for UML...')
@@ -313,7 +318,7 @@ class LinuxSourceTree:
 			return self.build_config(build_dir, make_options)
 
 		existing_kconfig = kunit_config.parse_file(kconfig_path)
-		self._ops.make_arch_qemuconfig(self._kconfig)
+		self._ops.make_arch_config(self._kconfig)
 		if self._kconfig.is_subset_of(existing_kconfig) and not self._kunitconfig_changed(build_dir):
 			return True
 		print('Regenerating .config ...')
-- 
2.37.0.rc0.104.g0611611a94-goog