From 747bfaf3a9d2f3cd51674763dc1f7575100cd200 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Mon, 22 Jan 2024 16:36:07 +0000 Subject: [PATCH] qemu-options.hx: Improve -serial option documentation MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The -serial option documentation is a bit brief about '-serial none' and '-serial null'. In particular it's not very clear about the difference between them, and it doesn't mention that it's up to the machine model whether '-serial none' means "don't create the serial port" or "don't wire the serial port up to anything". Expand on these points. Signed-off-by: Peter Maydell Reviewed-by: Daniel P. Berrangé Reviewed-by: Philippe Mathieu-Daudé Message-id: 20240122163607.459769-3-peter.maydell@linaro.org --- qemu-options.hx | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/qemu-options.hx b/qemu-options.hx index 484cc21c1f..40e938c487 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -4129,7 +4129,8 @@ SRST This option can be used several times to simulate up to 4 serial ports. - Use ``-serial none`` to disable all serial ports. + You can use ``-serial none`` to suppress the creation of default + serial devices. Available character devices are: @@ -4151,10 +4152,17 @@ SRST [Linux only] Pseudo TTY (a new PTY is automatically allocated) ``none`` - No device is allocated. + No device is allocated. Note that for machine types which + emulate systems where a serial device is always present in + real hardware, this may be equivalent to the ``null`` option, + in that the serial device is still present but all output + is discarded. For boards where the number of serial ports is + truly variable, this suppresses the creation of the device. ``null`` - void device + A guest will see the UART or serial device as present in the + machine, but all output is discarded, and there is no input. + Conceptually equivalent to redirecting the output to ``/dev/null``. ``chardev:id`` Use a named character device defined with the ``-chardev``