qemudriver: Add support for additional disk options

Adds support to pass additional disk options to QEMU when creating the
drive. This can be helpful for example to pass different "cache" options
that may affect performance.

Signed-off-by: Joshua Watt <Joshua.Watt@garmin.com>

CHANGES.rst

@@ -10,6 +10,8 @@ New Features in 23.1
 - A new log level called ``CONSOLE`` has been added between the default
   ``INFO`` and ``DEBUG`` levels. This level will show all reads and writes made
   to the serial console during testing.
+- The `QEMUDriver` now has an additional ``disk_opts`` property which can be
+  used to pass additional options for the disk directly to QEMU
 
 Bug fixes in 23.1
 ~~~~~~~~~~~~~~~~~

doc/configuration.rst

@@ -2483,6 +2483,7 @@ Arguments:
   - boot_args (str): optional, additional kernel boot argument
   - kernel (str): optional, reference to the images key for the kernel
   - disk (str): optional, reference to the images key for the disk image
+  - disk_opts (str): optional, additional QEMU disk options
   - flash (str): optional, reference to the images key for the flash image
   - rootfs (str): optional, reference to the paths key for use as the virtio-9p filesystem
   - dtb (str): optional, reference to the image key for the device tree

labgrid/driver/qemudriver.py

@@ -40,6 +40,7 @@ class QEMUDriver(ConsoleExpectMixin, Driver, PowerProtocol, ConsoleProtocol):
         boot_args (str): optional, additional kernel boot argument
         kernel (str): optional, reference to the images key for the kernel
         disk (str): optional, reference to the images key for the disk image
+        disk_opts (str): optional, additional QEMU disk options
         flash (str): optional, reference to the images key for the flash image
         rootfs (str): optional, reference to the paths key for use as the virtio-9p filesystem
         dtb (str): optional, reference to the image key for the device tree
@@ -64,6 +65,9 @@ class QEMUDriver(ConsoleExpectMixin, Driver, PowerProtocol, ConsoleProtocol):
     disk = attr.ib(
         default=None,
         validator=attr.validators.optional(attr.validators.instance_of(str)))
+    disk_opts = attr.ib(
+        default=None,
+        validator=attr.validators.optional(attr.validators.instance_of(str)))
     rootfs = attr.ib(
         default=None,
         validator=attr.validators.optional(attr.validators.instance_of(str)))
@@ -146,20 +150,23 @@ def get_qemu_base_args(self):
             disk_format = "raw"
             if disk_path.endswith(".qcow2"):
                 disk_format = "qcow2"
+            disk_opts = ""
+            if self.disk_opts:
+                disk_opts = f",{self.disk_opts}"
             if self.machine == "vexpress-a9":
                 cmd.append("-drive")
                 cmd.append(
-                    f"if=sd,format={disk_format},file={disk_path},id=mmc0")
+                    f"if=sd,format={disk_format},file={disk_path},id=mmc0{disk_opts}")
                 boot_args.append("root=/dev/mmcblk0p1 rootfstype=ext4 rootwait")
             elif self.machine == "q35":
                 cmd.append("-drive")
                 cmd.append(
-                    f"if=virtio,format={disk_format},file={disk_path}")
+                    f"if=virtio,format={disk_format},file={disk_path}{disk_opts}")
                 boot_args.append("root=/dev/vda rootwait")
             elif self.machine == "pc":
                 cmd.append("-drive")
                 cmd.append(
-                    f"if=virtio,format={disk_format},file={disk_path}")
+                    f"if=virtio,format={disk_format},file={disk_path}{disk_opts}")
                 boot_args.append("root=/dev/vda rootwait")
             else:
                 raise NotImplementedError(