Quoting Pedro Zorzenon Neto ([EMAIL PROTECTED]): > On Fri, Jul 20, 2001 at 12:42:13PM +0100, David Wright wrote: > > Do you mean this package? > > > > "Programmer for Atmel AVR microcontrolers that uses PC parallel port > > Yes. > > > If so, I'm not sure why you think it needs to be setuid. Just > > chgrp somegroup /dev/lp0 (or whichever port) and put yourself > > (and any others) into somegroup. > > I tried /dev/lp* and couldn't make the program work with it.
I should have looked back at what I had done. I didn't use /dev/lp* but a device of my own making /dev/pp125 which is major 125, minor 0 (i.e. in the range reserved for users). But chgrp it just the same. > This program uses a specific hardware connected to the printer port. It has > to read some bits of the port and write other bits in patterns which has to > change in some microseconds. > > That is why it uses lowlevel ioperm, inb, outb to IO 0x378 (or other IO, at > user option[1]) and runs setuid root. I used a kernel module, which saves using ioperm and setuid root. The module loads automatically when anyone (allowed) opens the device. > I think (not sure about all architectures) that because of this, it will run > only in i386 machines. If I used /dev/lp* it would run in all machines. If > someone knows how to use lp device for this specific purpose, please write me. Are you sure you aren't writing /dev/lp* to mean a special device with LP_MAJOR = 6, and hence the lp.o module. That won't work because lp.o only drives printers - it doesn't do arbitrary bit-twiddling. My module didn't use any architecture-specific headers, so I guess it should work on any architecture. However, I had no hardware to test that assertion. > [1] root must edit a config file to say which ports the user can choose. A module might look at /etc/modules.conf similarly. Cheers, -- Email: [EMAIL PROTECTED] Tel: +44 1908 653 739 Fax: +44 1908 655 151 Snail: David Wright, Earth Science Dept., Milton Keynes, England, MK7 6AA Disclaimer: These addresses are only for reaching me, and do not signify official stationery. Views expressed here are either my own or plagiarised.
