Linux is not about choice [was Re: Fedora too cutting edge?]

[Andrew Farris]

Arthur Pemberton wrote:
> On Jan 11, 2008 2:30 PM, Les Mikesell <lesmikesell at gmail.com> wrote:
>> It doesn't seem as sensible as being able to plug into a known
>> controller position and get a known device name, particularly in the
>> scenario where the drives aren't hot-plug and you want to access a bunch
>> of new ones after a reboot and know which is which.
> 
> Frankly i like this idea, but I'm unsure of the practicality of it:
> 
> What is the highest level which is even aware of the physical location
> of said device? I would imagine the BIOS knows, and maybe some really
> low level kernel modules but anything above that?

udev is fully aware of the physical location, because it knows the communication 
bus addressing to the device itself (/dev/disk/by-path).  What Les is asking for 
is a consistent guaranteed device node naming scheme, which makes good sense for 
machines with few devices (desktops, small servers) and less sense for larger 
systems.  The facts are the older scheme wasn't guaranteed to be deterministic, 
it just seemed to be because the kernel would probe / name the devices in 
sequential order, and its no longer guaranteed to do that (that still doesn't 
mean anything is named randomly).

I suppose someone could have additional udev rules that would follow the older 
naming scheme at the same time as the new one... just doing the 'magic 
guesswork' to make sure things always got named in the predictable ordering.

-- 
Andrew Farris <lordmorgul at gmail.com> <ajfarris at gmail.com>
  gpg 0xC99B1DF3 fingerprint CDEC 6FAD BA27 40DF 707E A2E0 F0F6 E622 C99B 1DF3
No one now has, and no one will ever again get, the big picture. - Daniel Geer
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