On Fri, Mar 20, 2026 at 11:52:09PM -0400, Onana Onana Xavier Manuel wrote: > I had a programming question. Is it possible to have a WSDISPLAYIO_MODE_DUMBFB > rendered on only one tty instead of having the mmap memory affecting every > tty despite the socket only targetting one.
No, it's not. To do what you want to do, you need to move away from dumbfb and on to something more complicated. To help you find the best solution, it would be help to have some more details about exactly what you are trying to do: What sort of program is this? Is it intended as a programming exercise, or to solve a particular local problem, or is it being developed for public release and intended to be portable to other systems? What hardware are you developing this on? The reason for asking is that a lot of common hardware does not support dumb framebuffer mode at all. If you are on amd64 and have this working, quite likely you are using efifb. The most common display hardware on that platform is probably inteldrm, which does NOT support dumbfb mode, (look at the source and you'll quickly see that). The closest thing that is available for what you want to do is to the kernel mode setting subsystem. This is a _big_ leap forward from using dumbfb to plot points. To get an idea of what is involved, have a look at: # man drm-kms Unless you are guru level with OpenBSD, you won't get this working in ten minutes. Be prepared for a lot of trial and error, and a lot of frustration trying to find the information you need. I do a lot of work on the rasops and wscons subsystems, (far more than what I have published), and honestly, I almost never touch the drm-kms stuff. Is there any reason why you are avoiding using X11 to write this graphical program? Xlib programing is awkward and non-intuitive, but if you already know dumbfb, then you can probably master the basics of Xlib over a weekend.
