gem(4)-related panic?

["John D. Baker" <jdbaker%mylinuxisp.com@localhost>]

My PowerMac G4 (AGP Graphics) recently panicked with (transcribed by
hand from console):

trap: pid 239.1 (make): user read DSI trap @ 0x2b3 by 0x181c460 *DSISR 0x40000000, err=14)
gem0: can't load rx DMA map 79, error = 22
panic: gem_add_rxbuf
Stopped in pid 0.2 (system) at  netbsd:vpanic+0x140:    addi    r4, r0, 0x0
0x10003cf0: at panic+0x4c
0x10003d30: at gem_add_rxbuf+0x2a8
0x10003d50: at gem_rint+0x170
0x10003db0: at bem_intr+0x184
0x10003df0: at pic_handle_intr+0x190
0x10003e30: at trapstart+0x6b0
0x10003f00: at idle_loop+0xdc
0x10003f20: at cpu_lwp_bootstrap+0xc
saved LR(0x5a5a5a56) is invalid.
db>

Issuing "reboot" at DDB prompt seemed to hang.  Upon pressing the reset
switch, the machine sounded its startup chord, but the display remained
blank.  Power-cycle has same effect.  There is no indication that it
has probed for the USB keyboard even after significant time since reset
or power-up.

Potential hardware issues aside, has anyone seen anything like this
since the recent changes to gem(4)?

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