[lfs-support] "Interesting" Names
beesnees at grm.net
Tue Nov 26 09:03:44 PST 2013
On 11/26/2013 07:53 AM, William Harrington wrote:
> On Nov 25, 2013, at 8:06 PM, Dan McGhee wrote:
>> There were many allusions to the "new naming convention." enpxx for
>> ethernet and wlpxx for wireless. Where does this name convention
>> exist? I remember that xlnglp posted about what he had discovered in
>> the "different" names, but I can't find what he wrote. I don't
>> if he had identified a source.
> Possibly it came from here: http://fedoraproject.org/wiki/Features/ConsistentNetworkDeviceNaming
> Check out biosdevname
> William Harrington
Thanks, William. That link led down an interesting path. It appears that
this "name thing" originated at Dell. I don't know if the fellow who
came up with the idea is a maintainer for UDEV or not. Anyway, The above
link led me to this:
It is an interesting discussion on how to implement or cancel the "name
thing" in udev. This, and William's suggestion, led me to "biosdevname."
It is a utility to take a kernel device name and return "the BIOS-given
name it 'should' be." (That from the biosdevname man page.)
[semi-rant]There is no indication of the identity of the "true BIOS name
Also from the biosdevname man page:
> The *physical* policy is the current default. However, when invoking
> biosdevname in udev rules, one should always specify the policy you
> want, as the default has changed over time.
> The *physical* policy uses the following scheme:
> em<port>[_<virtual instance>]
> for embedded NICs
> p<slot>p<port>[_<virtual instance>]
> for cards in PCI slots
> *all_ethN* policy makes a best guess at what the device order
> should be, with embedded devices first, PCI cards in ascending
> slot order, and ports in ascending PCI bus/device/function order
> breadth-first. However, this policy /does/ not work if your PCI
> devices are hot-plugged or hot-pluggable, including the virtual
> functions on an SR-IOV device. In a hot-plug scenario, each
> separate udev instance will be invoked in parallel, while the
> device tree is still being populated with new devices. Each udev
> instance will see a different PCI tree, and thus cannot provide
> consistent enumeration. Use of this policy should be limited to
> only scenarios where all PCI devices are present at boot (cold-plug).
So, it appears that this "name thing" is a "udev thing" and not a
"kernel thing." If my conclusions are correct, then I still wonder why
Alan's NIC, which is the same as mine, got a different name. The only
difference I know of so far is that he used LFS_SVN and I used LFS-7.4.
I'm discounting the kernel difference. I don't know if there's any
difference in results between UDEV-206 (LFS-7.4) and UDEV-208(LFS-SVN).
The only other possible difference is that Alan may have added "UDEV
Extras from BLFS.
On the other hand, I can understand another possible difference unless I
don't understand what "hot-plug" means. To me it's the ability to "plug
something in" while the computer is running and have it work--much like
a USB device. If my NIC is hot-pluggable, I would have to open the
laptop case to remove it.
Also, in the last 3-4 months, I've not seen anyone encounter this
situation but Alan. Does it exist in LFS, as written, yet?
I personally don't care what my NIC is named. I just want to be able to
make it work if it doesn't.
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