Re: [PATCH v2 7/7] n_tty: Provide an informational line on VSTATUS receipt

From: Pavel Machek
Date: Thu Aug 01 2019 - 06:10:18 EST


> > The use-case for this is different: the ^T-line as proposed by this
> > patch is for the user that interacts with a system through a terminal, who
> > wants to be informed not about the whole system (sort of what SysRq-t
> > tells you), but about what they run on that particular tty.
> Ok, fair enough, although if you just add a new sysrq option for "what
> is running on this tty", would that help resolve this?

This is meant for unpriviledged users, unlike sysrq.

> > This is much less about "why does my system/kernel seem to hang?" or
> > exposing low-level internals (registers, hrtimers, locks, ...), and more
> > about "is my SSH terminal session unresponsive?" and "I ran a command,
> > it doesn't finish, how's it doing?".
> > e.g. A user might want to know if their SSH connection is alive without
> > interrupting anything, while having no access both to SysRq and console,
> > and no one in fg pgrp actually handles SIGINFO.
> If you have access to a tty, you should have access to sysrq, right?

No. This is supposed to work over ssh. SysRq is not supposed to work
over ssh; that would be a security hole.

Best regards,
(cesky, pictures)

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