Re: gem driver for sun4m

> On Jul 14, 2026, at 3:58=E2=80=AFPM, [email protected] wrote:
>=20
> Hi,
>=20
> I've been experimenting with the gigabit fiber optic SBus cards that =
Sun released for the Ultra 1 and 2. There's a driver for them in =
sparc64, and I've been able to get it working on regular sparc as well.

Very cool!

> The gem driver for SBus only required a minor change to config values =
for burst size. There was also the iommu_dmamap_load_mbuf() function =
left unimplemented in iommu.c for sparc, which gem required.
>=20
> In my original testing earlier this year, my implementation of the =
iommu code was a stub just to get things running. I later learned from =
miod on the OpenBSD project that Mark Kettenis got these cards working =
back in 2009. I've since been working on porting his changes to iommu =
back to NetBSD.
>=20
> So far, it seems to be working out quite well. I'm able to get about =
the speeds you'd expect running with flash storage through a BlueSCSI =
and I haven't seen any issues with stability. I'm preparing a patch now =
pending a regression test on sparc64. I'd appreciate feedback or testing =
from other port-sparc users, if there's any interest.

Looking forward to seeing your patch.

-- thorpej