[Savage40] Savage Frame Buffer

[Alex Deucher]

--- Tim Roberts <timr at probo.com> wrote:

> Nathan Olberding wrote:
> 
> >Hmmm... then why is it there?
> >  
> >
> 
> The only devices which really need a custom frame buffer driver are 
> devices that cannot be placed into a graphics mode using VESA calls.
> 
> The standard frame buffer driver interface offers just enough
> services 
> to make a graphics-mode console work.  That means mode sets, font 
> handling, character writes, cursor handling, and window scrolling in 
> units of lines and characters.  It offers less than the old VGA INT
> 10 
> interface.  It also returns a pointer to the frame buffer bytes,
> which 
> is what 99.9% of programs use it for, including the XFree86 fbdev
> driver.
> 
> It has no standard ioctls for doing bitblts, rectangle fills, line 
> drawing, or bitmap drawing.  Any fancy drawing is done by the 
> applications directly, straight into the frame buffer.  A driver is
> free 
> to offer custom ioctls for these, of course, but applications won't
> know 
> about them.
> 
> Now, it is possible my knowledge is outdated.  I haven't followed the
> 
> 2.6 kernels closely enough.
> 
> -- 
> - Tim Roberts, timr at probo.com
>   Providenza & Boekelheide, Inc.
> 

pretty much.  the kernel framebuffer drivers are useful for setting
hi-res modes for consoles and they can provide limited accel in some
cases.  Some can also bring up cards on systems like PPC that don't
have an x86 bios for vesa or vga mode.  some can also provide console
support for things like dualhead and tv-out.  Jon Smirl and others are
working on merging the drm and fb drivers to provide a single device
interface for access to the video card and kernel support for posting
and switching which card is using the legacy vga ports.

Alex



		
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