Re: [Qemu-devel] [PATCH] sdl shared buffer support

[Daniel P. Berrange]

On Wed, Sep 03, 2008 at 05:11:47PM +0100, Stefano Stabellini wrote:
> Stefano Stabellini wrote:
> 
> > Blue Swirl wrote:
> > 
> >> This function is broken if BGR-ness of the display is not equal to
> >> emulated device BGR-ness.
> >>
> > 
> > good catch!
> > I am going to send an updated version of this and the opengl patch soon
> > to fix the issue.
> > 
> 
> I replied to this email a little too fast: reading vga.c and
> vga_template.h again more carefully it occurred to me that the guest is
> always RGB, only the host can set the sdl display to BGR.
> Hence we don't need to handle this case in sdl_setdata, because if there
> is any difference in depth or subpixel ordering between host and guest,
> is up to SDL_BlitSurface to solve it.
> 
> But there is a similar issue that I wasn't handling: guest big endian
> and host little endian or vice versa.
> In fact I need to set different colour masks in sdl setdata according to
> the guest endianness.

Just to complicate things still further, the endianness of the host running
QEMU may not be the same as the endianness of the X server display. 

Daniel
-- 
|: Red Hat, Engineering, London   -o-   http://people.redhat.com/berrange/ :|
|: http://libvirt.org  -o-  http://virt-manager.org  -o-  http://ovirt.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: GnuPG: 7D3B9505  -o-  F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|