Re: [Qemu-devel] Gives user ability to select endian format for video display - fixes Mac OS X guest color issue.

[Gerd Hoffmann]

  Hi,

> However, you should specify it whatever the host endianness and the host
> OS is.  If this is not the case, you're just exchanging a bug with another.
> 
> If something
> 
> a) works with Linux host but not with Mac OS X host
> 
> b) and works with Linux guest but not with Mac OS X guest
> 
> the only logical explanation is that you have more than one bug, and
> they somehow cancel each other.

It isn't that simple I think.  Linux and MacOS X using different video
modes could also have this effect.  Also there are a number of ways
linux can drive the video card, depending on the kernel version.
kernels 3.14+ have a drm driver for the qemu stdvga, which runs the card
with 32bpp (if enabled).  On older kernels the only option is offb,
which IIRC by default runs with 8bpp modes.  Also offb has quirks to set
the palette registers on the qemu stdvga.

So, one interesting question is how MacOS X drives the video card?  Just
using what openfirmware has initialized?  Which video mode?

Turning on DEBUG_VGA in vga.c should help shed a light on what the guest
is doing and which video mode is active.

Also: what UI is in use?  cocoa?  gtk?  sdl?  Has using another ui
(assuming it is available on macosx hosts) any effect?

cheers,
  Gerd