CSMI questions

[mikem]

All,
I hate to dredge this up again, but, when Eric Moore submitted changes for MPT
Fusion driver containing the CSMI ioctls it was rejected. There was talk on
the linux-scsi list about it being a horrible interface, among other things.
There were also comments about there being a Linux only approach. Personally,
I like that idea but it's not good from a business perspective. Especially
because HP, Dell, and others support more than one OS. Having a unique set of
management apps for each OS would be very cumbersome.

We've also been looking at how to use sysfs rather than ioctls.
 
Some look reasonable, others seem to be restricted by sysfs itself. 
1. only ASCII files are allowed
2. if multiple attributes are contained in one file, who parses out the data?
3. one buffer of size (PAGE_SIZE) may not hold all of the data required

Maybe I'm missing something. If any sysfs experts would like to help me
understand, I'm all ears.

The spec is available at: http://www.t10.org/ftp/t10/document.04/04-345r1.pdf

I'd also like an (brief) explanation of why ioctls are so bad. I've seen the 
reasons of them never going away, etc. But from the beginning of time (UNIX)
ioctls have been the preferred method of user space/kernel communication.
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