A possible issue with SDHC

The new SDHC capable RH controller works great. I’ve mainly used it for 2.11BSD so far, and everything works faster, more responsive, and nicer with it. Compiling the kernel, playing with Ingres – no problems at all.
But this little command line:

while true; do /usr/games/fortune;echo;echo;sleep 2;done

after a random number of fortunes bombs out with the message

true: cannot execute

and it doesn’t with the old style controller.
I’m not sure I’m able to explain properly how weird this is. But it correlates perfectly well with the new controller, and I’m able to reproduce it easily (although it may take a couple of hours of running the while loop before it occurs). All other likely causes – clock speed too high, card broken, issues with the board or FPGA, memory etc – have been excluded.
I’ve been thinking for a couple days on how to isolate the issue, but that isn’t easy – it doesn’t predictably occur, and I’m not sure yet where to go looking. Maybe the best for now is to continue with what I wanted to do anyway – check the old XXDP test programs against the new controller, and add multiple disk support. There’s a good chance that will help finding what causes this.
In the meantime, I don’t think this should stop you from using the SDHC version – other than this weirdness, it seems pretty stable, and everything else I’ve thrown at it works fine. But keep an eye on things, do your backups, and be sure to contact me if you see something similarly weird happening!