svn commit: r346052 - head/sys/dev/usb/net
Rodney W. Grimes
freebsd at gndrsh.dnsmgr.net
Tue Sep 3 14:07:15 UTC 2019
> On 4/9/19 12:48 PM, Rodney W. Grimes wrote:
> >> On 4/9/19 9:59 AM, Ian Lepore wrote:
> >>> On Tue, 2019-04-09 at 09:33 -0700, John Baldwin wrote:
> >>>> On 4/9/19 9:17 AM, Ian Lepore wrote:
> >>>>> On Tue, 2019-04-09 at 09:11 -0700, John Baldwin wrote:
> >>>>>> On 4/9/19 6:54 AM, Ganbold Tsagaankhuu wrote:
> >>>>>>> Author: ganbold
> >>>>>>> Date: Tue Apr 9 13:54:08 2019
> >>>>>>> New Revision: 346052
> >>>>>>> URL: https://svnweb.freebsd.org/changeset/base/346052
> >>>>>>>
> >>>>>>> Log:
> >>>>>>> In some cases like NanoPI R1, its second USB ethernet
> >>>>>>> RTL8152 (chip version URE_CHIP_VER_4C10) doesn't
> >>>>>>> have hardwired MAC address, in other words, it is all zeros.
> >>>>>>> This commit fixes it by setting random MAC address
> >>>>>>> when MAC address is all zeros.
> >>>>>>>
> >>>>>>> Reviewed by: kevlo
> >>>>>>> Differential Revision:
> >>>>>>> https://reviews.freebsd.org/D19856
> >>>>>>
> >>>>>> It would be best to not use a purely random mac address and to
> >>>>>> use
> >>>>>> the
> >>>>>> function kevans@ added recently. That function generates a MAC
> >>>>>> address
> >>>>>> from the FreeBSD OUI using a cryptographic hash so you get a
> >>>>>> stable address across boots on a given host.
> >>>>>>
> >>>>>
> >>>>> How could that possibly work? If it's not random, you can't have
> >>>>> two
> >>>>> such devices on the same network. If it is random, it's not stable
> >>>>> from one boot to the next.
> >>>>
> >>>> It uses the UUID and interface name as input into the hash.
> >>>
> >>>> The UUID is per-host.
> >>>
> >>> Oh, so it only works on x86 (or I guess any system that has something
> >>> like a bios that can provide you with a uuid that doesn't change from
> >>> one boot to the next).
> >>
> >> The function is in one centralized place where you are free to add other
> >> data as input into the hash. We do always generate a uuid that we save
> >> on boot if we aren't seeded with one by firmware, though that is probably
> >> too late for this driver (so +1 may in fact be a better route). It should
> >> be fine for psuedo interfaces created post-boot though even on non-x86 due
> >> to /etc/rc.d/hostid. Pure random MAC's are not really great either.
> >
> > Cant the loader load /etc/rc.d/hostid and put it in something that
> > the kernel could get at, or a module written that handles this?
>
> It's a different file, and yes in theory the loader could look at the file
> and set UUID and hostid env vars. However, that's a no-op for most use
> cases. If other platforms have some kind of firmware-provided thing that
> isn't a UUID, it would be good to teach the centralized function about
> those as an input to the hash, but at least that can be done in place
> rather than having open-coded MAC generators in various drivers.
Simple enough, can one not just store /etc/rc.d/hostid into
a env variable in /boot/loader.conf too on those platforms
that do not have a uuid mechanism?
--
Rod Grimes rgrimes at freebsd.org
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