Re: Sane behavior of fbset

[John Zielinski <grim@undead.cc>]

Antonino A. Daplas wrote:

>1.  Revert to 2.4 behavior.  This is easy to add since fbdev already has a notifier 
>support. (I already have working code for this). Of course, stty will still work.
>
>  
>
Definitely #1.   The functionality is very easy to add to the kernel as 
most of it is already in place.

>2.  Make the set_var ioctl return immediately if the vc_mode of the current display is 
>KD_TEXT. Basically, fbset becomes an informational utility only. I don't know the 
>repercussions of this with userland fb applications though.
>
>  
>
Several people have already started doing work adding fb mode changing 
to sysfs.  Fbset will most likely become a wrapper around the sysfs 
interface.

>3.  Modify fbset (and other similar utilities, if there are any) so it also issues an 
>'stty-like' call after a 'set_var' call.   
>
>  
>
Ug, please no.  That's just asking for trouble.  Now the app would have 
to figure out what the font size is so that adds a third call.  If the 
app gets the calculation between x-y -> row-col wrong then the screen 
would be messed up at best or we'd get an infinite loop at worse (like 
one of the earlier patches to the kernel did).

>Note: As mentioned by many people before, it's almost impossible to completely 
>preserve per-console mode info because of the lack of a per-display var.  So even 
>if we agree to implement #1,  it cannot completely match 2.4 behavior. Also, the lack
>of per-display var means that drivers must be able to handle mode changes without 
>any help.  James' fb_find_mode support in fbcon_resize does partly alleviate this 
>limitation.
>  
>
Several people on the list are pushing to have per-console var put back 
in.   This is a far as it should go for the 2.6.x series.  There are 
more elaborate solutions proposed for the 2.7 kernel.

John




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