Re: gem driver for sun4m

[Jason Thorpe <thorpej%me.com@localhost>]

> On Jul 14, 2026, at 3:58 PM, erik%eriklabine.com@localhost wrote:
> 
> Hi,
> 
> 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.
> 
> 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.
> 
> 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