[Dave Hudson <dave@humbug.demon.co.uk> writes:]
>I think this tends to depend on the hardware you have available - a couple
>of years back I came across this problem and wrote a test program that
>looked for the spurious interrupts.
I've been in communication with the FreeBSD and NetBSD folks, and all of
us have seen this problem across a wide range of systems.
>It would be nice if there was a way of getting an IRQ based version running
>as well as a polled version (an ideal case for a "stat" field perhaps?).
The nice thing about the iret stub is that I minimize the cost of taking
these useless interrupts. Having to save all the state needed to go up
into C source code would make this long-lived misfeature cost even more
CPU cycles.
>Thinking about it, I'm pretty sure that IRQ7 (and IRQ5 for lp2) must be
>pretty reliable on a lot of systems, otherwise there'd be no chance of
>getting PLIP links to work. I suspect that if Tommy Thorn's reading this he
>can probably give some more details.
No, it's not reliable on a large number of systems. All the software you
see on DOS/Windoze machines for doing stuff over the LP port all handles
this problem using timeouts, polls, and spin-loops.
Andy
Received on Sun Mar 13 16:27:51 1994
This archive was generated by hypermail 2.1.8 : Wed Sep 21 2005 - 21:02:16 PDT