The recent discussion about kcopy() reminds me of something,
also pcb related:
The i/o permissions bitmap in the i386 TSS is utterly useless
nowadays, except in special cases like vm86. Actual hardware
isn't limited to the first 1024 I/O ports, and all userlevel
software I've seen in the last years uses the iopl() mechanism
to get I/O access.
Besides that, the implementation is conceptually broken since
LWPs were introduced: it should be per-process, but the per-lwp
PCBs are never synchronized afaics.

So I'm for deprecating the -IOPERM part in the sysarch()
system call. This would save us some bytes in the TSS needlessly
copied on LWP creation.
I'd suggest to make it an option for now which is off per default.

Opinions?

best regards
Matthias