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[0/2] Optionally allow ttynull to be selected as a default console

Message ID 20250117043427.1512743-1-adamsimonelli@gmail.com
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Series Optionally allow ttynull to be selected as a default console | expand

Message

adamsimonelli@gmail.com Jan. 17, 2025, 4:34 a.m. UTC 
From: Adam Simonelli <adamsimonelli@gmail.com>

When switching to a CONFIG_VT=n world, at least on x86 systems,
/dev/console becomes /dev/ttyS0. This can cause some undesired effects.
/dev/console's behavior is now tied to the physical /dev/ttyS0, which when
disconnected can cause isatty() to fail when /dev/ttyS0 is disconnected,
and users who upgrade to a theoretical vt-less kernel from their
distribution who have a device such as a science instrument connected to
their /dev/ttyS0 port will suddenly see it receive kernel log messages.

When the new CONFIG_NULL_TTY_CONSOLE option is turned on, this will allow
the ttynull device to be leveraged as the default console. Distributions
that had CONFIG_VT turned on before will be able to leverage this option
to where /dev/console is still backed by a psuedo device, avoiding these
issues, without needing to enable the entire VT subsystem.

Adam Simonelli (2):
  ttynull: Add an option to allow ttynull to be used as a console device
  tty: Change order of ttynull to be loaded sooner.

 drivers/tty/Kconfig   | 18 +++++++++++++++++-
 drivers/tty/Makefile  |  3 ++-
 drivers/tty/ttynull.c | 16 +++++++++++++++-
 3 files changed, 34 insertions(+), 3 deletions(-)