Re: [Qemu-devel] [PATCH v2] stop using stdio for monitor/serial/etc with -daemonize

[Peter Maydell]

On 26 September 2012 09:17, Michael Tokarev <address@hidden> wrote:
> On 26.09.2012 12:00, Peter Maydell wrote:
>
>>> I know lots of people use -nographic -daemonize to run headless
>>> guests in background (like, for example, a router).  I guess it
>>> come way before -vga option has been introduced, but at least I
>>> know about -vga (but not about -vga none).  For one, I never saw
>>> -display before.  And it looks like -nographic is a synonym for
>>> -display none, and -curses is a synonym for -display curses.
>
> I mean, -nographic is about the same as -vga none -display none.

...except that it *also* messes around with where the serial output
goes and with the parallel port and maybe something else.

> What is equivalent of -nographic in terms of -vga/-display/-...?
> From the code it is something like
>
>  -vga none -display none -serial mon:stdio -parallel null

It's something like that. It would be nice to implement -nographic
as "this is an alias for ...." but IIRC it isn't quite doable.
(maybe I misremember)

> (this is the code I tried to patch).
>
> Note: this, compbined with -daemonize, also has the same issue,
> namely, the tty is left in a bad state after qemu process backgrounded,
> and for the very same reason: -serial stdio switches the try into
> raw mode.  So this should be fixed too -- somehow, either by forbidding
> this combination completely or by silently substituting stdio for
> -serial with null.  But it will be done in a subsequent patch.
>
> Note also: by forbidding -nographic -daemonize, we'll break lots of
> existing setups too, and I still don't see why this combination is
> bad, I already demonstrated that it can be made to work in a more
> or less reasonable/expected way.

Because you've asked both "put me into the background" and "please
send stuff to stdio". Admittedly you've probably done that because
you didn't really understand that '-nographic' doesn't mean
'-display none', but you've still asked for a nonsensical combination.

-- PMM