Date: Sun, 17 Aug 2014 23:31:19 +0000 From: "Pokala, Ravi" <rpokala@panasas.com> To: "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org> Subject: Common storage of original MAC address Message-ID: <D0168955.11C3AD%rpokala@panasas.com>
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Hi folks, At attach-time, the NIC drivers call ether_ifattach(), which stores the MAC address in the sockaddr_dl. If the MAC is subsequently changed (like by adding the interface to a lagg), if_setlladdr() changes the value in the sockaddr_dl. At least, that's the way I'm reading things - is that correct? If so, then we do not keep a copy of the original MAC address. For a couple of reasons (diagnostics, asset tracking and reporting), it would be very nice if the original MAC were kept somewhere, even after the working MAC was changed by if_setlladdr(). Up till now, Panasas has been saving the original MAC in the softc of specific network drivers that we use, and making it accessible via a sysctl. That's something we have to do on a per-driver basis, and something we have to keep track of on our own. We'd like to put that information in a structure all the NIC drivers already use, and get that code upstream. Storing it would require a simple change to ether_ifattach() to stash it in the new location in addition to in the sockaddr_dl, and adding some standard way (a new ioctl or sysctl?) to access it. Notably, it would not require changing all the individual drivers.=20 Are there any objections to this idea? Any suggestions as to where we might stash the original MAC? Thanks, Ravi
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