Matthew Wilcox wrote:
> On Mon, Oct 15, 2007 at 04:26:04AM -0500, Rob Landley wrote:
>> Combining USB and IDE into the same /dev/sd? namespace makes enumerating the
>> IDE devices much harder than in the traditional "/dev/hdb doesn't move
>> without a screwdriver" model. The merger creates a new problem for IDE, one
>> which didn't exist before: the addition or removal of other unrelated types
>> of devices may change this device's location next boot. It may be possible
>> to add additional complication to the system to compensate, but what was the
>> advantage of merging the namespaces in the first place?
>
> It's not something anyone particularly set out to do, it's just how
> it worked out. It was justified by saying "ok, this goes from a 99%
> solution to a 96% solution, but there's 100% solution called uuids".
> I don't particularly agree with this line of argumentation, but it did
> hold sway.
Low-level networking drivers suggest a default interface name (per
interface or as a template like eth%d into which the networking core
inserts a lowest spare number). Userspace can rename interfaces, but
nevertheless it's nice to have different default kernel names for
ethernet, wlan etc..
Could low-level SCSI drivers provide similar name templates which give a
hint on the transport involved? It's a bit more difficult as with
networking interfaces though because
- SCSI devices can have sd, sr, st, osst, ch, sg interfaces,
- SCSI device files share a namespace with all other device files.
E.g.
/dev/sd-ide-b - second IDE HDD,
/dev/sd-iscsi-e - fifth iSCSI direct access device,
/dev/sr-sata-0 - first SATA CD-ROM,
/dev/sr-usb-0 - a USB CD-ROM,
/dev/st-fw-0 - a FireWire tape drive,
/dev/sda - a device whose transport driver didn't propose a name
Of course the really interesting names will still be provided by
udev-generated symlinks.
--
Stefan Richter
-=====-=-=== =-=- -====
http://arcgraph.de/sr/
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