On Saturday 03 December 2005 00:00, Jeff Dike wrote:
> On Fri, Dec 02, 2005 at 09:44:20PM -0600, Rob Landley wrote:
> > I've never used mconsole. Never needed it before.
> > Perhaps if I attach to a serial console instead of stdio I can send sysrq
> > that way...
> No. Just think a little. Banging on the SysRq key on your keyboard can't
> do anything but send SysRq to the host.
I know. That's why I asked. I thought there might be some other key
combination that could do the same thing for a UML console. (QEMU listens to
the tty to do various escapes in non-graphics mode, for example.)
> SysRq for a virtual machine has to be an out-of-band thing wrt the host.
Yeah, sending compressed data across the console becomes a bit dangerous
otherwise. But again, the difference between a pipe and a tty is that a tty
has out-of-band information attached.
Possibly a couple of different shift keys plus the character in question?
(Something X wouldn't intercept first, qemu uses ctrl-alt and it seems to
work for them.) According to man 4 console_ioctl, TIOCLINUX subcode 6 gives
me something called "shift_state", so maybe I can beat some information out
of the tty to tell when the user hit "ctrl-alt t" and turn that into sysrq-t?
In theory it might work both when stdin is a tty and via an xterm...
To-do item. The documentation on this sucks pretty badly...
> For UML, that's mconsole.
Except that serial consoles can also do sysrq. (I vaguely remember they send
a break signal or some such. Dunno how to do that on an emulated one...)
Steve Ballmer: Innovation! Inigo Montoya: You keep using that word.
I do not think it means what you think it means.