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. -- John Baldwin _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
