git: 78537728efc5 - main - Document tunable net.link.epair.ether_gen_addr

The branch main has been updated by ronald:

URL: https://cgit.FreeBSD.org/src/commit/?id=78537728efc5387558c97ba2730ce746d6259013

commit 78537728efc5387558c97ba2730ce746d6259013
Author:     Ronald Klop <ronald@FreeBSD.org>
AuthorDate: 2025-08-11 13:51:16 +0000
Commit:     Ronald Klop <ronald@FreeBSD.org>
CommitDate: 2025-08-12 14:36:52 +0000

    Document tunable net.link.epair.ether_gen_addr
    
    Approved by:    hrs
    Fixes:  590493c1419092e98f7ad1dcadb886973502341e ("if_epair(4): use ether_gen_addr(9) for stable MAC address")
    MFC after:      1 week (together with the tunable)
    Differential Revision: https://reviews.freebsd.org/D51861
---
 share/man/man4/epair.4 | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/share/man/man4/epair.4 b/share/man/man4/epair.4
index 4bcb54c936cb..342b15b5612a 100644
--- a/share/man/man4/epair.4
+++ b/share/man/man4/epair.4
@@ -25,7 +25,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd March 18, 2015
+.Dd August 12, 2025
 .Dt EPAIR 4
 .Os
 .Sh NAME
@@ -79,12 +79,24 @@ and
 Like any other Ethernet interface, an
 .Nm
 needs to have a network address.
-Each
+If the tunable
+.Va net.link.epair.ether_gen_addr Ns
+=0, each
 .Nm
-will be assigned a locally administered address by default,
+will be assigned a random locally administered address,
 that is only guaranteed to be unique within one network stack.
-To change the default addresses one may use the SIOCSIFADDR ioctl(2) or
-ifconfig(8) utility.
+The tunable
+.Va net.link.epair.ether_gen_addr Ns
+=1 will generate a stable MAC address with
+.Fx
+OUI using
+.Xr ether_gen_addr 9 .
+This tunable defaults to 1 in
+.Fx 15.0 and might be removed in
+.Fx 16.0 .
+To change the default addresses one may use the SIOCSIFADDR
+.Xr ioctl 2 or
+.Xr ifconfig 8 utility.
 .Pp
 The basic intent is to provide connectivity between two virtual
 network stack instances.