Mouse, thanks very much for taking the time to comment. On 06/06/2015 02:35 PM, Mouse wrote: >> Am I correct to assume that the GPU must support 4bpp in order for it >> even to be possible for the X-server to propagate a 4-plane visual to >> a client? > No. However, it is substantially more difficult for an X server to > present a visual that the hardware doesn't support, which is probably > why the server you have doesn't do it. Well-behaved clients must be > prepared to handle whatever capabilities the server presents; the > problem here is that the client you have handles the server you have by > complaining and dying. > > Depending on what other capabilities the client is using, you might be > able to get the overlay effect using colourmap hackery with > comparatively small code changes. What PseudoColor or DirectColor > visuals are available?
If you are talking about hacking the x-client, no chance. At least, that would probably entail unacceptable cost for the customer, who does not have the source. >> If yes, how can I determine if a GPU supports 4bpp? > Read the documentation, of course, or contact the manufacturer's > support department. Kind of hopeless in the case of manufacturers of mass-market hardware... >> Nvidia is very sparing with the information in their specs for the >> Quadro 400 GPU. > You may be out of luck without repalcing the hardware, then. (That's > one of the prices of buying undocumented hardware....) The Quadro 400 is coincidence. The test hardware was randomly chosen before all this 4-plane stuff was known. The solution can be anything reasonable. >> Assuming I can find a GPU that supports/offers 4bpp, does anyone know >> an X-server product/project that can provide 4-plane overlays? > You probably do not need a GPU. The era when 4-bit visuals were common > was full of dumb memory-mapped framebuffers; modern CPUs are fast > enough that they can probably fake up a 4-bit overlay visual and still > run at least as fast as the hardware your client software was designed > to run against. > > I'm not sure how hard it would be to do. My X server hackery has never > included faking something the hardware doesn't support, so my > experience is rather limited in that direction. But I've done DDX > layers for at least three widely disparate framebuffers, and I feel > reasonably confident what you want could be done. Depending on the cost, hacking the X-Server might be an option. I have presented MS-Windows as a given here, but in fact I could also use Linux. Do any possibilities involving Linux occur to you? cheers, Rob
