Is kernel or userspace responsible for rotating framebuffer to match screen

I'm working on embedded device with screen rotated 90 degrees clockwise: screen controller reports 800x600 screen, while device's screen is 600x800 portrait.

What do you think, whose responsibility it is to compensate for this: should开发者_如何学C kernel rotate framebuffer to provide 800x600 screen as expected by upper-level software or applications (X server, bootsplash) should adapt and draw to rotated screen?

Every part of stack is free software, so there are no non-technical problems for modification, the question is more about logical soundness.

It makes most sense for the screen driver to do it - the kernel after all is supposed to provide an abstraction of the device for the userspace applications to work with. If the screen is a 600x800 portrait oriented device, then that's what applications should see from the kernel.

yes,I agree, The display driver should update the display accordingly and keep the control

Not sure exactly how standard your embedded device is, if it is running a regular linux kernel, you might check in the kernel configurator (make xconfig, when compiling a new kernel) , one of the options for kernel 2.6.37.6 in the device, video card section, is to enable rotation of the kernel messages display so it scrolls 90 degrees left or right while booting up.

I think it also makes your consoles be rotated correctly after login too.

This was not available in kernels even 6-8 months ago, at least not available in kernel that slackware64 13.37 came with about that time.

Note that the bios messages are still rotated on a PC motherboard, but that is hard-coded in the bios, which may not apply to the embedded system you are working with.

If this kernel feature is not useful to you for whatever reason, how they did it in the linux kernel might be good example of where and how to go about it. Once you get the exact name of the option from "make xconfig", it should be pretty easy to search where ever they log the kernel traffic for that name and dig up some info about it.

Hmmm. I just recompiled my kernel today, and I may have been wrong about how new this option is. Looks like it was available with some kernel versions before the included-with-Slackware64 versions that I referenced. Sorry!