On Monday October 15, [EMAIL PROTECTED] wrote: > > This is my objection. Even when enumerating multiple devices of the same > type > is tricky, enumerating multiple devices of _different_ types should not be. > There's a great big type indicator that is being _deliberately_ ignored, and > large classes of devices (millions of laptops) where you know there's only > going to be _one_ instance of a given type.
My perspective is different. The range of addressing option for "all disk devices" is far too rich to be able to assign a stable device number every device: there are multiple, multi-dimensional addressing scheme, and some devices might not even have a stable address at all (e.g. USB?). So the reality of dealing with disk devices is that you cannot provide a stable single-number naming scheme for all devices on all machines. Therefore it is best to not have stable single-number naming schemes for any devices on any machines. Why? Because it ensure there will not be any second class citizens. If some devices that are even reasonably common (e.g. IDE drives) are stable, then some application developers or system integrators will work under the assumption of stability and whatever they build will break when you try it on different hardware. This happened during the early days of SCSI support - code assumed the stability of major/minor numbers and so did not work properly with SCSI which cannot provide that stability in general. Having a totally uniform approach makes development and testing a lot easier - there are fewer special cases. I would prefer that 'total uniformity' went even further than /dev/sd?? to /dev/disk??. i.e. Anything that is or behaves substantially like a disk drive should be "/dev/diskXX", where numbers are assigned sequentially on discovery. (I wonder why we need /dev/scdX to be separate from /dev/sdX). Note that stable names a still a very real option. udev provides several. /dev/disk-by-path/XXX will be stable for lots of "screwed in" devices. /dev/disk-by-id will be stable for devices the report a unique id. etc. The different between IDE, SATA, SCSI and even USB is peripheral for the large majority of uses, and I think maintaining the distinction in the major/minor number or in the "primary" /dev name is - for the above reasons - more of a cost that a value. NeilBrown - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
