There are those who would have you believe that Damon Muller wrote: > Hi Chris, > > Quoth Krzys Majewski, > > I don't know how to say this properly.. when backing up files from my > > IDE hard drive to my parallel port ZIP100 drive, the machine > > occasionally blocks: it's like everything freezes for about half a > > minute before I can do anything again. This only happens when the ZIP > > drive is running (not sure if it's R or W or both). This is with > > kernel 2.2.17, using the imm driver as a module. I've set all the > > default "safe" options for the driver, like "slow and reliable" or > > whatnot. Is this a kernel bug? IMM driver bug? User bug? Feature? > > Help? chris > > After having recently resurected my parallel zip drive and connecting it > once again to my debian machine (decided that it might be a good idea to > back up my thesis...), I've also experienced similar problems. > > Using the zip drive under both windoze and linux I've seen it eat up so > much cpu time that the system goes very choppy and is unusable while the > transfer is going on. I don't know if this is a bug in anything in > particular, or if writing that much data through the parallel port is > just a really tough job. > > Unless anyone else can offer a more concrete suggestion, I'd recomend > that when copying large files to your zip, it's probably a good > opportunity to go and make yourself a coffee! >
It's possible that Linux is using PIO mode for data transfers over your parallel port instead of DMA. Check /proc/parport/0/hardware (assuming you're using the first parallel port). If there's no DMA, make sure the port is in ECP mode with a DMA assigned to it in your CMOS settings, and read the parport docs in the kernel source.
