Minor vt issue (probably a race)

[Aleksandr Rybalko]

On Thu, 10 Apr 2014 20:01:47 -0400
Glen Barber <gjb at FreeBSD.org> wrote:

> On Thu, Apr 10, 2014 at 04:58:51PM -0700, Kevin Oberman wrote:
> > vt has been working for me for a while, but I have encountered an annoying
> > issue. Only a little annoying, but it looks like a race and my have less
> > obvious impacts. Since the patch to prevent crashes when resuming with vt,
> > I have seen the problem.
> > 
> > When I suspend, the system sometimes switches to vty0 before suspending,
> > but often does not. When it fails to switch on suspend, it does so a few
> > seconds after resume. I have been able to simply switch back to X
> > (<ALT+F9>) and everything was normal. If that i its only impact, it's no
> > big deal, but I fear that this may have deeper implications that I don't
> > see, so I wanted to report it.
> 
> I've seen this too.  But, it's been too inconsistent for me to report.
> 
> The other thing I noticed, maybe unrelated, is X is no longer "laggy"
> for me after resume since the relevant commit.
> 
> Related?  I have no idea.
> 
> Glen
> 

Hi,

Glen, if you about broken Xorg screen, then I should say -
kern.vt.suspendswitch sysctl designed to help with that. So if you have
value other than zero, machine going to ttyv0 before suspend, and back
on resume. This is make notification to Xorg or drm to redraw (maybe
even reallocate FB memory used by Xorg).

Kevin, thanks for report, I will look what happen in that case. 
It maybe related to some busyness, Xorg's or whole machine, so Xorg do
not answers vt(4)'s request to VT switch.

Thanks a lot!

WBW
-- 
Aleksandr Rybalko <ray at freebsd.org>