ioctl
Matt Cheselka
cheselka at tucana.noao.edu
Tue Jan 11 13:33:04 EST 2000
Hello all again,
I'm now attempting to use ioctl to talk to a piece of hardware that I'm working with and have again gotten stuck. Here's how I'm doing it:
>>> import fcntl
>>> fd = open ("/dev/random", "rb") // the random number generator
>>> RNDGETENTCNT = -2147200512 // get entropy count
>>> val = fcntl.ioctl (fd.fileno(), RNDGETENTCNT, xxx)
Traceback (innermost last):
File "<stdin>", line 1, in ?
NameError: xxx
so I try this:
>>> xxx = 0
>>> val = fcntl.ioctl (fd.fileno(), RNDGETENTCNT, xxx)
Traceback (innermost last):
File "<stdin>", line 1, in ?
IOError: (14, 'Bad address')
So it appears as though I'm not passing the correct value of 'xxx' since it
looks like fcntl.ioctl is interpreting 'xxx=0' to be the address of where to
place the result, which is in the ROM and not legal.
So I've got two questions:
1. is this essientially the correct way to do ioctl stuff or is there
a better way?
2. how do I pass this method the correct address?
TIA,
Matt Cheselka
cheselka at noao.edu
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