[Qemu-devel] Re: [[RfC PATCH]] linux fbdev display driver prototype.

[Stefano Stabellini]

On Fri, 21 May 2010, Julian Pidancet wrote:
> This looks very promissing.
> 
> I just got a couple of observations:
> 
> - Your patch does not work on my machine with the vesafb driver. It reports 
> "can't handle 8 bpp frame buffers". It turns out that the vesafb driver seems 
> to initialize the framebuffer in PSEUDOCOLOR mode. I think we should add a 
> piece of code which tries reinitialize the framebuffer with the suitable 
> parametters (32bpp/TRUECOLOR). It works fine with inteldrmfb though.
> 

32bpp would be ideal, but we could probably handle 24 and 16 bpp too

> - You should register a Display Allocator and override the 
> create_displaysurface() method like I did in the DirectFB driver. This way 
> you save qemu a data copy. fbdev_render_32() should only be used when the 
> guest framebuffer is not compatible with the physical framebuffer (guest_bpp 
> != physical_bbp || guest_linesize != physical_linesize).
> 

agreed

> - A cool feature would be to be able to stretch the guest display in 
> fullscreen. My DirectFB driver implements a fullscreen toggle command by 
> pressing the Ctrl-Alt-Return keys. I think Stefano added a SDL zoom feature a 
> while ago which we could reuse for this.
> 

sdl_zoom.c is actually generic and not SDL specific, so it shouldn't be
difficult to reuse it here