qemu-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [PATCH 7/9] fbdev: move to pixman


From: Stefano Stabellini
Subject: Re: [Qemu-devel] [PATCH 7/9] fbdev: move to pixman
Date: Thu, 20 Sep 2012 16:20:43 +0100
User-agent: Alpine 2.02 (DEB 1266 2009-07-14)

On Thu, 20 Sep 2012, Gerd Hoffmann wrote:
>   Hi,
> 
> > It might be a good idea to get rid
> > of DisplayAllocator altogether.
> 
> After some digging in the source code:  Yes, I think so.
> 
> Look, we have *two* concepts for avoiding memcpy:
> 
> The first is the DisplayAllocator.  Only implemented by SDL, which is
> scheduled to be downgraded by anthonys gtk patches.  Doesn't really fit
> into the concept of displaychangelisteners coming and going at runtime,
> and also not of having multiple displaychangelisteners (like sdl+vnc at
> the same time).  It allows vga emulation to render directly into a SDL
> buffer.
> 
> The second is qemu_create_displaysurface_from().  It allows vga
> emulation hand out a surface with direct pointer to the guests video
> memory for displaychangelisteners to read from.
> 
> You can't have both (i.e. the guest will never ever write directly into
> the SDL buffer), there will always be at least one memcpy.
> 
> So what happens in practice?
> 
> In any graphics mode relevant today vga emulation will use
> qemu_create_displaysurface_from().  Whenever a DisplayAllocator is
> present or not doesn't make any difference then.

Unfortunately if my memory doesn't fail me, Windows uses 24 bpp.
So actually the DisplayAllocator interface is the one that is going to be
used all the time.

<sarcasm> You have got to love Windows </sarcasm>



reply via email to

[Prev in Thread] Current Thread [Next in Thread]