Messages in this thread | | | Date | Thu, 6 Aug 1998 21:42:45 -0400 | From | "Theodore Y. Ts'o" <> | Subject | Re: Is Documentation/ioctl-numbers.txt still accurate? |
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Date: Thu, 6 Aug 1998 12:33:11 -0400 From: steve_snyder@gilbarco.com (Steve Snyder)
File Documentation/ioctl-numbers.txt documents the IOCTL "magic" numbers already in use by the 2.1.15 kernel (that's 15, not 115). This brings to mind 2 questions:
1. How accurate is this document today? A whole lotta changes have been made to the kernel in the 7 months since this document was written. Am I really on safe ground if I choose a number not listed as already being in use?
My guess is that it probably isn't completely up to date. On the other hand, it isn't a disaster if there's a conflict, since the main reason for the ioctl's to be unique is so that something bad won't happen if (for example) a CD-ROM ioctl is used on a file descriptor corresponding to a serial port. This is nice, but isn't absolutely necessary.
2. Is there a way (other than trial-and-error) to determine if a given "magic" number is already in use by the kernel?
Grep is your friend when touring through the kernel sources. :-)
- Ted
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