Hi Bart, On Mon, Nov 08, 2004 at 02:21:16PM +1300, Bart Oldeman wrote: > > Speed shouldn't be such a big deal: according to > http://www.ussg.iu.edu/hypermail/linux/kernel/0303.0/0978.html > you can only do about 300000 inb's and outb's per second > anyway.
Speed betweeen a virtualized and non-virtualized parallel port I/O can be a big deal in my experience. I have at least one device that gives up when parallel ports are passed through in non-fast mode. It operates with tristate data lines and one strobe pin. I'm not sure what the problem is, only that the port must be fast for it to work. On a (much?) faster machine, probably the port virtualization would not affect it. But requiring the use of ppdev doesn't make sense in this case. By the way, I have benchmarked ppdev vs raw portio performance on this device with a linux program. The difference is quite significant (ppdev only performs around 60% of the rawio speed IIRC). On a better device which uses interrupt or DMA driven I/O, the difference would not be that significant, but on this device, transfer rate depends on how fast the registers of parallel port can be "twiddled", so it is greatly affected by any delay therein. -- Ryan Underwood, <[EMAIL PROTECTED]> - To unsubscribe from this list: send the line "unsubscribe linux-msdos" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
