[Qemu-devel] sun framebuffer selection (was option-rom)

[Bob Breuer <breuerr@mc.net>]

Blue Swirl wrote:
>  but again: should we have a new machine with cg14 or
> some switch to select TCX vs. cg14?
>
> Maybe the recently proposed machine subtype patches could help here.
>   
Well, let's try to figure out a method of selecting the framebuffer
type.  I'll try to list some of the options, even if they might be
ridiculous.

1) Use the -vga option.  I know TCX and cg14 are not vga, but I think
it's the closest existing command line option available.

2) Switch based on the -g WxH option.  At the moment, the TCX emulation
doesn't really handle anything other than 1024x768, so switch to cg14
for other resolutions if supported.

3) Use some other existing command line option, -device, -set or
-global?  Might work, but the syntax may not be easy to remember.

4) Machine subtype.

5) New command line option.  Anything above might be better.

6) New machine type.  Is it a big enough feature to demand it's own
machine type?  Maybe, but see next option.

7) Select as default video for SS-20.  The SS-10 and SS-600MP are
already very similar.  This would allow for some differentiation between
the machines, but there could still be an option to switch back to TCX. 
Note that TCX was really only available for the SS-4 and SS-5.


Is there anything else that I missed?

I'm going to go ahead with option 2 in the short term.  I'm inclined to
narrow it down to options 1, 4, and 7.  I know that 7 would have
backwards compatibility concerns.  The cg14 seems to have at least the
same capabilities as TCX so there shouldn't be any loss of
functionality.  Even though SS-20 is not the default machine, do you
know of any OS that works with the sun4m implementation today but
doesn't have a cg14 driver?  Possible downside to cg14 for video is that
any "acceleration" is handled by the SX pixel processor which has no
available documentation.  TCX also has some amount of unimplemented
acceleration.

Bob