On Fri, Aug 09, 2024 at 08:38:37PM +0200, Alexander Bluhm wrote:
> 
> On sparc64 it does not panic.  Jumbo frames are not well supported
> on this machine, I guess some bugs in the IOMMU implementation.
> Other drivers also have problems with jumbo on sparc64.  Only part
> of my tests pass.  This is not a regression.

does this help?

Index: machdep.c
===================================================================
RCS file: /cvs/src/sys/arch/sparc64/sparc64/machdep.c,v
diff -u -p -r1.218 machdep.c
--- machdep.c	22 May 2024 05:51:49 -0000	1.218
+++ machdep.c	10 Aug 2024 04:51:22 -0000
@@ -993,7 +993,7 @@ _bus_dmamap_load_mbuf(bus_dma_tag_t t, b
 
 			if (i > 0 && pa == (segs[i - 1].ds_addr +
 			    segs[i - 1].ds_len) && ((segs[i - 1].ds_len + incr)
-			    < map->_dm_maxsegsz)) {
+			    <= map->_dm_maxsegsz)) {
 				/* Hey, waddyaknow, they're contiguous */
 				segs[i - 1].ds_len += incr;
 				continue;