> This might not be as niche as you might think. I'm one of the
> Linux kernel maintainers for s390. Many of us do the vast majority of
> their development work natively on s390 systems via SSH from Fedora
> laptops.
I first wanted to echo and confirm what Niklas says here.
The crux of this issue seems to be "the code in the X server that does this is virtually untested" so would more attention being paid to this code help? I can't make any promises, but it would be valuable to know if this, or something else, is needed. I will also bring this to the attention of the Open Mainframe Project Linux Distributions Working Group, since all of the distros use this byte-swapped code.
The people I learned coding and how to break code in the 80's always looked at byte-swapping in any project for problems. Most of the code was usually cargo culted from other projects or some sci.comp newsgroup. It might work but it would usually then be plastered in with fragile code or you would find that something 3 or 4 layers up broke.
Currently there is only one byte-swapped architecture which Fedora runs on. There are about 82 Fedora instances on it and ~900 instances using EPEL. However, I think this request is coming more from the current maintainers of X. They also do not have ready access to byte-swapped systems so have no way to say 'oh this works' or not. I think X and other code fixed to deal with byte-swapping is going to need focus as I expect this change will 'filter' into other operating systems over time.