svn commit: r271023 - stable/10/sys/dev/vt

[Ed Maste]

On 3 September 2014 10:07, Alexey Dokuchaev <danfe at freebsd.org> wrote:
> On Wed, Sep 03, 2014 at 02:00:37PM +0000, Ed Maste wrote:
>> New Revision: 271023
>> URL: http://svnweb.freebsd.org/changeset/base/271023
>>
>> Log:
>>   MFC r270280 by dumbbell: vt(4): Pause the flush timer while swithing window
>>
>>     This fixes bad looking refresh when switching window: squares instead
>>     of text, flashing screen, and so on. In the worst case, vt_flush() came
>>     at a very inappropriate timing and the screen was not refreshed at all
>>     (leaving squares all over the place).
>>
>>     This doesn't fix the flickering of the screen with vt_vga, because the
>>     sync signal is temporarily stopped and the video memory is cleared.
>
> Will this improve the current situation with switching ttys on the console?
> Right now it takes considerable time to switch, and sometimes the image is
> not properly restored.

This should address the corruption on vt switch; I don't believe it
will have an effect on the switching time.

> I'm also wondering why on PowerPC vt(4) behaves much better (switching is
> instant, no artifacts at all).

The VGA vt(4) issues all stem from the relatively complex and arcane
VGA hardware and a somewhat limited vt_vga implementation.  Most of
the issues have been sorted out in HEAD by dumbbell@ and those are in
the pipeline to be merged.