virtme-ng: redirect kernel log to stderr in interactive mode

virtme/architectures.py

@@ -124,7 +124,7 @@ def earlyconsole_args():
 
     @staticmethod
     def serial_console_args():
-        return ["console=ttyS0"]
+        return ["virtme_console=ttyS0"]
 
     @staticmethod
     def config_base():
@@ -225,7 +225,7 @@ def earlyconsole_args():
 
     @staticmethod
     def serial_console_args():
-        return ["console=ttyAMA0"]
+        return ["virtme_console=ttyAMA0"]
 
     def kimg_path(self):
         return "arch/arm/boot/zImage"
@@ -274,7 +274,7 @@ def earlyconsole_args():
 
     @staticmethod
     def serial_console_args():
-        return ["console=ttyAMA0"]
+        return ["virtme_console=ttyAMA0"]
 
     def kimg_path(self):
         return "arch/arm64/boot/Image"
@@ -334,7 +334,7 @@ def qemuargs(is_native, use_kvm):
 
     @staticmethod
     def serial_console_args():
-        return ["console=ttyS0"]
+        return ["virtme_console=ttyS0"]
 
     def kimg_path(self):
         return "arch/riscv/boot/Image"

virtme/commands/run.py

@@ -986,23 +986,38 @@ def do_it() -> int:
     qemuargs.extend(["-net", "none"])
 
     if args.graphics is None and not args.script_sh and not args.script_exec:
-        # It would be nice to use virtconsole, but it's terminally broken
-        # in current kernels.  Nonetheless, I'm configuring the console
-        # manually to make it easier to tweak in the future.
         qemuargs.extend(["-echr", "1"])
         qemuargs.extend(["-serial", "none"])
-        qemuargs.extend(["-chardev", "stdio,id=console,signal=off,mux=on"])
 
-        qemuargs.extend(arch.qemu_serial_console_args())
+        if args.verbose:
+            # Check if we have permission to access the current stderr.
+            if not can_access_file("/proc/self/fd/2"):
+                print(
+                    "ERROR: not a valid pts, try to run vng inside tmux or screen",
+                    file=sys.stderr,
+                )
+                sys.exit(1)
 
-        qemuargs.extend(["-mon", "chardev=console"])
+            # Redirect kernel messages to stderr, creating a separate console
+            qemuargs.extend(["-chardev", "file,path=/proc/self/fd/2,id=dmesg"])
+            qemuargs.extend(["-device", arch.virtio_dev_type("serial")])
+            qemuargs.extend(["-device", "virtconsole,chardev=dmesg"])
+            kernelargs.extend(["console=hvc0"])
 
-        if args.verbose:
+            # Unfortunately we can't use hvc0 to redirect early console
+            # messages to stderr, so just send them to the main console, in
+            # this way we don't lose early printk's in verbose mode and we can
+            # catch potential boot issues.
             kernelargs.extend(arch.earlyconsole_args())
-        qemuargs.extend(arch.qemu_nodisplay_args())
+
+        qemuargs.extend(["-chardev", "stdio,id=console,signal=off,mux=on"])
+        qemuargs.extend(["-serial", "chardev:console"])
+        qemuargs.extend(["-mon", "chardev=console"])
 
         kernelargs.extend(arch.serial_console_args())
 
+        qemuargs.extend(arch.qemu_nodisplay_args())
+
         # PS/2 probing is slow; give the kernel a hint to speed it up.
         kernelargs.extend(["psmouse.proto=exps"])
 

virtme/guest/virtme-init

@@ -310,7 +310,11 @@ if [[ -n "${user_cmd}" ]]; then
 fi
 
 # Figure out what the main console is
-consdev="`grep ' ... (.C' /proc/consoles  |cut -d' ' -f1`"
+if [[ -n "${virtme_console}" ]]; then
+    consdev=${virtme_console}
+else
+    consdev="`grep ' ... (.C' /proc/consoles  |cut -d' ' -f1`"
+fi
 if [[ -z "$consdev" ]]; then
     log "can't deduce console device"
     exec bash --login  # At least try to be helpful
@@ -335,6 +339,10 @@ if [[ ! -e "/dev/$consdev" ]]; then
     exec bash --login
 fi
 
+# Redirect current stdout/stderr to consdev
+exec 1>/dev/${consdev}
+exec 2>&1
+
 # Parameters that start with virtme_ shouldn't pollute the environment
 for p in "${!virtme_@}"; do export -n "$p"; done