Am 2018-07-11 17:48, schrieb Eduardo Habkost:
"none" looked like a false positive when I first looked, but now
I think it's not. Shouldn't it set default_display="none"?
I think that there is some other logic burried that these machine
doesn't get a graphics display. But overall it is indeed not clearly
defined.
But see below.
If the patch is applied to 3.1 then I think there is enough time to
fix
issues caused by the patch. Additionally, a warning could be put in
the
ChangeLog for 3.0 that in 3.1 that the default mode will be std unless
machines define an own default. This is should be enough time for
people to
complain or to fix things.
I don't think we will really make user-visible changes: we can
simply work to keep existing behavior, but the difference is that
this will be implemented by setting default_display explicitly on
all machines.
Even if all machines were using explicit default settings the patch will
affect machines that are not inside the QEMU tree. If the patch is to be
applied as it is these are affected. To warn users (or devs in this
case) about this, an entry in the ChangeLog would be appropriate.
If the patch is to be applied to 3.0 then all non-ppc ones need to be
reconsidered.
The "important" ppc machines have been fixed already. I can do the
remaining
if this is wanted.
This part worries me: do we have other machines that are broken
right now?
I don't know which of them are broken or how this can be elaborated, but
they are potentially affected. For instance, the sam460ex platform
doesn't care about this setting, I can say that it is not broken. Other
platforms like the mac apparently were broken (and fixed in the
meantime). It is hard to tell which of them are really broken without
someone that knows the platform trying it and telling it. 'Make check'
did catch only one single case. It could also be that nobody cares about
other affected machines.
Overall I think the patch is an improvement over the previous state as
preferring the Cirrus doesn't make much sense if most machines don't
prefer it. The more I think over it, the more I think that the concept
needs further fine-tuning though (not necessarily in this patch).
If OTOH it would become a requirement for machines to set a default
display then this fallback logic could removed. Instead, qemu could
simply bailout on machines that define no default display (including
"none") and also bailout when the requested default display is not
available. This would be checkable by 'make check'. I still think that
the most common value can be a default (strictly bailing out when it is
not available unlike it is done now), but this is a matter of taste I
guess.
Bye
Sebastian