Messages in this thread | | | Date | Sun, 12 Dec 2004 18:16:38 -0800 | From | "Randy.Dunlap" <> | Subject | Re: dummy help on io |
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Gene Heskett wrote: > On Sunday 12 December 2004 19:11, Randy.Dunlap wrote: > >>Gene Heskett wrote: >> >>>Greetings; >>> >>>I've ordered the device drivers book from O-Reilly but it will be >>>a few days getting here. >> >>Get it online: >>http://lwn.net/Kernel/LDD2/ > > > Thanks, but my printer is down, I mde the mistake of installing > cups-1.1.22. But I'll go get it anyway.
Sure, just look at it on-screen (or print very selected pages of it).
>>>I'm trying to mod the GPL'd archive PIO.tar.gz, so it will build a >>>driver for a pci card with 3 each 82C55's on it, and I *think* I'd >>>have it working with the first of the 3 chips if I could figure >>>out what to do about using the call "iopl(3);" on installing >>>the driver, and conversely an "iopl(0);" at rmmod time. >> >>Where is that coming from? I don't see it in the tarball >>or the web site (if I'm looking at the right place). >> http://ieee.uow.edu.au/~daniel/software/robotd/ > > > <http://ieee.uow.edu.au/~daniel/software/PIO/> > >>>I'm told this is required to gain access perms to addresses above >>>0x3FF. The call "ioperm" is used below that I've been told. >> >>iopl() and ioperm() are userspace calls that call (g)libc. >>The kernel doesn't call them. > > > So my driver module does need them?
A kernel driver (whether built into vmlinux or a loadable module) cannot use them and does not need them.
>>>Unforch, an "insmod PIO io=0xf100" (where the card is addressed >>>at currently) is spitting out an "unresolved symbol" error for the >>>iopl call. >>> >>>Being a rank beginner at "pc" hardware, can someone give me a >>>checklist of things I've probably left out please? >> >>Can you put the iopl() call into your app instead? > > > I can try it in the examples demo.c which I've modified to run > the motor 10 revolutions, if it runs. 1 step/sec. That runs > without any errors *if* I take the iopl() back out of the driver > and insmod it. > > >>or into a shell script that forks the app (since the iopl >>man page says: Permissions are inherited by fork and exec.) >> >> >>>Kernel is 2.4.25-adeos. With the module "rtai" inserted when emc >>>is running for realtime control purposes. >>> >>>The card is pure hardware, no bios, only address decoding that >>>can set the base address anyplace in the first 64k of address >>>space in a step of 4 sequence from 0xnn00-0xnn0C for the 4 >>>ports of chip 1, 0xnn10-1C for chip 2, etc, where the nn is the >>>dipswitch setting.
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