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SubjectRe: [PATCH v2 0/7] TTY Keyboard Status Request
On Tue, Jun 25, 2019 at 07:11:46PM +0300, Arseny Maslennikov wrote:
> This patch series introduces TTY keyboard status request, a feature of
> the n_tty line discipline that reserves a character in struct termios
> (^T by default) and reacts to it by printing a short informational line
> to the terminal and sending a Unix signal to the tty's foreground
> process group. The processes may, in response to the signal, output a
> textual description of what they're doing.
>
> The feature has been present in a similar form at least in
> Free/Open/NetBSD; it would be nice to have something like this in Linux
> as well. There is an LKML thread[1] where users have previously
> expressed the rationale for this.
>
> The current implementation does not break existing kernel API in any
> way, since, fortunately, all the architectures supported by the kernel
> happen to have at least 1 free byte in the termios control character
> array.
>
> The series should cleanly apply to tty-next.
>
> To thoroughly test these, one might need at least a patched stty among
> other tools, so I've brought up a simple initrd generator[2] which can
> be used to create a lightweight environment to boot up in a VM and to
> fiddle with.
>
> [1] https://lore.kernel.org/lkml/1415200663.3247743.187387481.75CE9317@webmail.messagingengine.com/
> [2] https://github.com/porrided/tty-kb-status-userspace
>
> v2 <- v1: removed useless debugging bits.
>
> Discussion of v1:
> https://lore.kernel.org/lkml/20190605081906.28938-1-ar@cs.msu.ru/
>
> Arseny Maslennikov (7):
> signal.h: Define SIGINFO on all architectures
> tty: termios: Reserve space for VSTATUS in .c_cc
> n_tty: Send SIGINFO to fg pgrp on status request character
> linux/signal.h: Ignore SIGINFO by default in new tasks
> tty: Add NOKERNINFO lflag to termios
> n_tty: ->ops->write: Cut core logic out to a separate function
> n_tty: Provide an informational line on VSTATUS receipt
>
> arch/alpha/include/asm/termios.h | 4 +-
> arch/alpha/include/uapi/asm/termbits.h | 2 +
> arch/arm/include/uapi/asm/signal.h | 1 +
> arch/h8300/include/uapi/asm/signal.h | 1 +
> arch/ia64/include/asm/termios.h | 4 +-
> arch/ia64/include/uapi/asm/signal.h | 1 +
> arch/ia64/include/uapi/asm/termbits.h | 2 +
> arch/m68k/include/uapi/asm/signal.h | 1 +
> arch/mips/include/asm/termios.h | 4 +-
> arch/mips/include/uapi/asm/signal.h | 1 +
> arch/mips/include/uapi/asm/termbits.h | 2 +
> arch/parisc/include/asm/termios.h | 4 +-
> arch/parisc/include/uapi/asm/signal.h | 1 +
> arch/parisc/include/uapi/asm/termbits.h | 2 +
> arch/powerpc/include/asm/termios.h | 4 +-
> arch/powerpc/include/uapi/asm/signal.h | 1 +
> arch/powerpc/include/uapi/asm/termbits.h | 2 +
> arch/s390/include/asm/termios.h | 4 +-
> arch/s390/include/uapi/asm/signal.h | 1 +
> arch/sparc/include/asm/termios.h | 4 +-
> arch/sparc/include/uapi/asm/signal.h | 2 +
> arch/sparc/include/uapi/asm/termbits.h | 2 +
> arch/x86/include/uapi/asm/signal.h | 1 +
> arch/xtensa/include/uapi/asm/signal.h | 1 +
> arch/xtensa/include/uapi/asm/termbits.h | 2 +
> drivers/tty/Makefile | 3 +-
> drivers/tty/n_tty.c | 70 ++++-
> drivers/tty/n_tty_status.c | 337 +++++++++++++++++++++++
> include/asm-generic/termios.h | 4 +-
> include/linux/sched.h | 7 +
> include/linux/signal.h | 5 +-
> include/linux/tty.h | 7 +-
> include/uapi/asm-generic/signal.h | 1 +
> include/uapi/asm-generic/termbits.h | 2 +
> 34 files changed, 457 insertions(+), 33 deletions(-)
> create mode 100644 drivers/tty/n_tty_status.c
>

> Date: Tue, 25 Jun 2019 19:11:46 +0300
Ping.

The series should cleanly apply to 5.3-rc2 and to tty-next as of writing
this email.
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