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

[Michael Tokarev <mjt@tls.msk.ru>]

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.

> -nographic does about three different things at once (and I think
> some of its effects aren't documented). It's a legacy option retained
> for backward compatibility with old command lines.

Sure.  Just like, for example, -stdvga was at the time being.

> If you want something that is non-confusing and makes sense, then
> use -display none to disable graphics, -serial stdio to send serial
> to stdio, and so on. These newer options do one clear thing each
> and can be combined straightforwardly.
> 
>> It looks like we have way too many confusing options doing the
>> same thing.  And I think they should be consistent, at least
>> when they SMELL like they do the same thing, instead of forbidding
>> one or another in some situations.
> 
> I'd love to drop -nographic but we'd break huge numbers of
> existing setups...

So let's make it actually work as expected till we're able to finally
drop it.

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

(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.

Thanks,

/mjt