On 01/05/2020 16:16, Andy Shevchenko wrote: > On Fri, May 1, 2020 at 2:11 PM Alper Nebi Yasak > <alpernebiyasak@xxxxxxxxx> wrote: >> I'm assuming "by default" here means "without console arguments" >> regardless of firmware requests. This paragraph (with small changes) is >> repeated on many other Kconfig descriptions (drivers/tty/serial/Kconfig, >> drivers/tty/serial/8250/Kconfig, arch/sparc/Kconfig from grepping for >> '/dev/tty0' on **/Kconfig). >> >> From Documentation/admin-guide/serial-console.rst: >> >>> You can specify multiple console= options on the kernel command line. >>> [...] >>> Note that you can only define one console per device type (serial, video). >>> >>> If no console device is specified, the first device found capable of >>> acting as a system console will be used. At this time, the system >>> first looks for a VGA card and then for a serial port. So if you don't >>> have a VGA card in your system the first serial port will automatically >>> become the console. >> >> and later on: >> >>> Note that if you boot without a ``console=`` option (or with >>> ``console=/dev/tty0``), ``/dev/console`` is the same as ``/dev/tty0``. >>> In that case everything will still work. > > I'm wondering if behaviour is changed if you put console=tty1 instead > of console=tty0. Just tested again with the QEMU aarch64 VM. Comparing console=tty1 and console=tty0 cases: /proc/consoles has tty1 instead of tty0 (both also has ttyAMA0), and `echo '/dev/console is here' >>/dev/console` goes to vt1 instead of the currently visible vt. Same difference before and after this patchset.
