ci: Fix test_serial_off

The integration test validating that --serial off works correctly was
not properly written as it was using the FW, which by default would use
the kernel command line found in the EFI partition. Unfortunately, this
kernel command line was including "console=ttyS0", which causes the
kernel to try to write to the serial port, even if there's no serial
port being emulated.

The problem is, when no emulation of the serial port is provided, the
default value returned on 0x3f8 is 0, which makes the guest kernel think
that some data needs to be read.

The only way to avoid all this is by ensuring we can control the kernel
command line by removing any occurence of "console=ttyS0" from it.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

tests/integration.rs

@@ -2326,17 +2326,28 @@ mod tests {
         });
     }
 
-    #[cfg_attr(not(feature = "mmio"), test)]
     fn test_serial_off() {
         test_block!(tb, "", {
             let mut clear = ClearDiskConfig::new();
             let guest = Guest::new(&mut clear);
+            let mut workload_path = dirs::home_dir().unwrap();
+            workload_path.push("workloads");
+
+            let mut kernel_path = workload_path;
+            kernel_path.push("bzImage");
+
             let mut child = GuestCommand::new(&guest)
                 .args(&["--cpus", "boot=1"])
                 .args(&["--memory", "size=512M"])
-                .args(&["--kernel", guest.fw_path.as_str()])
+                .args(&["--kernel", kernel_path.to_str().unwrap()])
                 .default_disks()
                 .default_net()
+                .args(&[
+                    "--cmdline",
+                    CLEAR_KERNEL_CMDLINE
+                        .replace("console=ttyS0,115200n8 ", "")
+                        .as_str(),
+                ])
                 .args(&["--serial", "off"])
                 .spawn()
                 .unwrap();