[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-ppc] [Qemu-devel] [PATCH v2 2/2] vga: don't pick cirrus by def

From: Sebastian Bauer
Subject: Re: [Qemu-ppc] [Qemu-devel] [PATCH v2 2/2] vga: don't pick cirrus by default
Date: Wed, 11 Jul 2018 19:00:54 +0200
User-agent: Roundcube Webmail/1.3.6

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
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.


reply via email to

[Prev in Thread] Current Thread [Next in Thread]