PIOSEGSZ-
Formerly, the amount of virtual address space in clicks
available for programmed I/O.
PIOMAP-
Formerly, determined the size of the map entry array used by
the kernel programmed I/O (PIO) breakup routine.
This routine allows device drivers to do
programmed I/O of large data blocks at interrupt level
by breaking the data blocks into smaller data units.
The buf breakup routine and async I/O both work a different way now,
and have no need for the PIO segment.
PIOMAXSZ-
Formerly, maximum number of pages to use at one time
for programmed I/O.
SEGMAPSZ-
Formerly, the amount of virtual address space in clicks
available for kernel mapping of user read/write requests.
Has been replaced by SEGKMEM_BYTES and SEGKMEM_PERCENT.
segkmap is no longer restricted to 16 MB of kernel virtual.
SYSSEGSZ-
Formerly, the amount of virtual address space in clicks
(pages) available for allocation.
This was used for either kma,
where the virtual addresses are backed by physical memory,
or for device memory mapped into the kernel.
Has been replaced by the combination of SEGKMEM_BYTES and
SEGKMEM_PERCENT.
KMA is no longer restricted to 16MB.