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

[Programmingkid]

On Jan 5, 2015, at 5:06 PM, Peter Maydell wrote:

> On 5 January 2015 at 21:27, Programmingkid <address@hidden> wrote:
>> This patches does the following:
>> 
>> - Allows user to select endian format of video display.
>> This allows Mac OS X to be used as a guest and show all its colors
>> correctly. Just add -display-endian-big to the command line to use
>> this feature.
> 
> I don't understand the purpose of this option. There are two
> video display endiannesses I can think of:
> 
> (1) The guest video device endianness. We should just get this
> correct according to the definition of what the hardware does
> (and it's not dependent on which host UI we're using)
> (2) The host graphics framebuffer endianness. We should
> automatically determine this by either asking the host's
> GUI about it or by just knowing it if the host is always one
> way. (This isn't dependent on what guest is running, either.)
> 
> So what is this option doing? It shouldn't be needed for either
> (1) or (2)...
> 
> thanks
> -- PMM

http://virtuallyfun.superglobalmegacorp.com/?p=3197
This is how Mac OS X looks like in QEMU with a Mac OS X host. The colors are 
all wrong. 

This patch fixes that problem so the colors look normal. Things aren't always 
so perfect with computers. Out of all the operating systems I have ran on 
qemu-system-ppc, Mac OS X is the only one that has this color issue. I'm not 
sure about Mac OS 9 yet. This solution does make using any operating system in 
QEMU display the correct colors. 

Your option 1. QEMU does not emulate any video card that shipped with a Mac. So 
we can't use this option. 

Option 2. I don't know what you mean by asking the host's GUI about it. I do 
know that having the user choosing the right option does work. 

Does any VGA genius know if there is some way to automatically detect the 
correct endianness? Or is little endian the format that was required by the 
standard?