Date: Tue, 03 Sep 2019 14:07:11 -0000 From: Ian Lepore <ian@freebsd.org> To: John Baldwin <jhb@FreeBSD.org>, Ganbold Tsagaankhuu <ganbold@FreeBSD.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r346052 - head/sys/dev/usb/net Message-ID: <969703ae8558b4b6f2930208e9c36927b546bb77.camel@freebsd.org> In-Reply-To: <33d96fdb-0218-6555-6f03-3105649a1904@FreeBSD.org> References: <201904091354.x39Ds9e6070857@repo.freebsd.org> <ea3cb1dd-585b-e60f-294a-743645492d69@FreeBSD.org> <bd56e7a51ccc99aca6300ddafa449e6de95a1e20.camel@freebsd.org> <33d96fdb-0218-6555-6f03-3105649a1904@FreeBSD.org>
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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). -- Ian > In this particular use case, the first USB device will > have a varying MAC address which is an input into the UUID. Though, > the other option this driver could use for this specific case would > be > to just take the first MAC address and +1 to get the second one. >
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