serial device debug

Author: tylerfanelli

src/vmm/src/builder.rs

@@ -588,7 +588,7 @@ pub fn build_microvm(
 
     // On x86_64 always create a serial device,
     // while on aarch64 only create it if 'console=' is specified in the boot args.
-    let serial_device = if cfg!(feature = "efi") {
+    let _serial_device = if cfg!(feature = "efi") {
         Some(setup_serial_device(
             event_manager,
             None,
@@ -600,6 +600,12 @@ pub fn build_microvm(
         None
     };
 
+    let serial_device = Some(setup_serial_device(
+        event_manager,
+        None,
+        Some(Box::new(io::stdout())),
+    )?);
+
     let exit_evt = EventFd::new(utils::eventfd::EFD_NONBLOCK)
         .map_err(Error::EventFd)
         .map_err(StartMicrovmError::Internal)?;
@@ -1663,7 +1669,7 @@ fn attach_console_devices(
     // The device mutex mustn't be locked here otherwise it will deadlock.
     attach_mmio_device(
         vmm,
-        "hvc0".to_string(),
+        "ttyS0".to_string(),
         MmioTransport::new(vmm.guest_memory().clone(), console),
     )
     .map_err(RegisterFsDevice)?;

src/vmm/src/vmm_config/boot_source.rs

@@ -7,7 +7,7 @@ use std::fmt::{Display, Formatter, Result};
 pub const DEFAULT_KERNEL_CMDLINE: &str = "reboot=k panic=-1 panic_print=0 nomodule console=hvc0 \
                                           rootfstype=virtiofs rw quiet no-kvmapf";
 #[cfg(feature = "amd-sev")]
-pub const DEFAULT_KERNEL_CMDLINE: &str = "reboot=k panic=-1 panic_print=0 nomodule console=hvc0 \
+pub const DEFAULT_KERNEL_CMDLINE: &str = "reboot=k panic=-1 panic_print=0 nomodule console=ttyS0 \
                                           root=/dev/vda rw quiet no-kvmapf";
 #[cfg(target_os = "macos")]
 pub const DEFAULT_KERNEL_CMDLINE: &str = "reboot=k panic=-1 panic_print=0 nomodule console=hvc0 \