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SubjectOrganization of Generic SCSI-Devices?


some comments and questions about the scsi-interface of linux.

First of all it is very poor documented (at least in
linux/Documents/scsi.txt) and this makes it hard to find all
out somebody might want to know.
(I know writing documentation is a pain, but perhaps somebody
wrote already something that could be included in the kernel

Ok, my questions:

My programm (X-CD-Roast, CD-Writer-Frontend) is using alot of generic
scsi-stuff. Recently some people told me that I use the /dev/sga, /dev/sgb..
devices, which are outdated. According to linux/Documentation/devices.txt
(in kernel 2.0+) the device-names /dev/sg0, /dev/sg1 ... should be used.

Nevertheless the sg-module itself reports still /dev/sga and so on.
This can be changed in line 505 of sg.c.
(Changing 'a'+sg_template.dev_noticed to '0'+sg_template.dev_noticed).

But this means that you can only use up to 10 generic scsi-devices..
- or we have to move up to /dev/sg10+. Or like the ttys are doing it
by creating a /dev/sga after /dev/sg9... But this would be MORE than
confusing to a lot of programms which expect /dev/sga being the first
and not the 10th device. What to do? (I know it is not very likely
to have more than 9 scsi-devices, but who knows? )

Another question derives from this...How many generic-devices can be
handled by the kernel? And how are they mapped if there are multiple
scsi-controllers in the system?
(first all on controller 1 and then all on controller 2 and so on?)

The device-system itself can handle up to 255 minor-numbers, right?
On my RedHat-based system MAKEDEV creates only 8 devices /dev/sga-h ..
The german SUSE-Distribution only got devices /dev/sg0-3.
(There I noticed the first time the changed sg-numbers)

Can I create myself more sg-devices by incrementing the minor-number?
(The device-name itself doesn't really matter in this case).

A lot of questions, I hope I somebody can help me.



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