On 9/8/2026 12:01 AM, andy pugh wrote:
I think that most of these would actually build with preempt-rt, but
are not built as they can't be tested.
(Ie, I think that it is a testing problem, not a building problem,
that has them omitted from the uspace builds)

I tested that assumption: with uspace flags, none of the seven C drivers 
compile as they stand:

- hal_stg, pci_8255, hal_ax5214h, hal_vti: asm/io.h, no userspace equivalent

- hal_motenc, opto_ac5: pci_get_device, ioremap_nocache, raw <linux/pci.h>

- hal_evoreg: closest, uses rtapi_io.h, but still calls ioremap/writew directly

- pcl720.comp: asm/io.h plus kernel types

Only pluto_servo/pluto_step compile today (userspace sys/io.h path since 2007)

So it is a build problem too, not only testing. The porting path exists
(rtapi_pci.h/rtapi_io.h shims, hm2_pci and hal_gm show how), but each
driver needs real work plus hardware to validate.

That leaves the direction question you didn't take a position on:

A. Port and keep maintained, on the assumption users exist but haven't
shown up yet. Cost: porting effort per driver, review bandwidth, and
code that ships untested anyway until a tester appears.

B. Deprecate now, bring back on request. Add the deprecation note,
announce on forum + mailing list, remove after one cycle. If a real user
 appears later for a specific card, the git history keeps the driver and
 porting it then is the same effort as porting it now, except then we
have a tester from day one.

I favor B. Shipping freshly ported drivers with zero hardware validation
 is the same untested state we have today, just with more code to
maintain. Do you see a concrete reason to prefer A for any specific
card?PS: Forum poll result: a pci_8255 user reported in on the forum. He is
running a 3.x RTAI kernel, so likely an old LinuxCNC release that will
keep working regardless of what master does. Unknown yet whether he
upgrades or would test a uspace port; forum went down before I could
follow up. Will update when I can reach him.

This is the distinction the poll needs to draw: "card still in service"
vs "card owner plans to upgrade past the removal". Only the second
argues for keeping or porting.

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