svn commit: r346052 - head/sys/dev/usb/net

[Rodney W. Grimes]

> 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?

> -- 
> John Baldwin
-- 
Rod Grimes                                                 rgrimes at freebsd.org