FreeBSD, Wake-on-LAN and HP Microservers – WOL compatible Ethernet

I’ve been having some difficulties getting Wake-on-LAN (WOL) to work with an HP Microserver thanks to its Broadcom Ethernet adapter not doing the business with the FreeBSD drivers – setting WOL in the Microserver BIOS doesn’t have any effect. I’m pleased to report a solution that works.

The on-board Broadcom Ethernet adaptor still refuses to play ball, for reasons described in my earlier post. The pragmatic solution is to use a better supported chip set and I’ve had no difficulties with Realtek (at the low end of the market) so it was an obvious choice. Just bung a cheap Realtek-based card in and use it as a remote “on” switch – what could possibly go wrong?

First off, the HP Microserver has PCI-Express slots, but weird looking ones. I’d assumed one was PCI when I’d glanced it, but it’s a PCIe 1-channel slot with something strange behind it – possibly a second 1-channel slot. The documentation says its for a remote management card; presumably one which doesn’t need access to the back. There’s a 16-channel PCIe next to it.All very curious but irrelevant here. The point is that you’ll need a PCIe Ethernet card – a surplus 100M PCI one with a well supported, bog-standard chip, won’t do. The PCIe cards tend to be 1Gb, and are therefore not as cheap.

The first card I bought was a TP-Link TG-3458, which has standard Realtek 8168B adapter chip. Or at least mine did; I note that there is a Mk2 version out there. Mine’s definitely a revision 1.2 PCB, but if you buy one now it may have the newer chip (which is a problem – read on below). Anyway, this Mk1 card worked like a charm. On sending it the magic packet and the Microserver bursts in to life. There’s only one snag: It has a full-height bracket and the Microserver has a half-height slot, so you have to leave the card floating in its socket. This works okay as long as no one trips over the cable.

My second attempt was an Edimax EN-9260TX-E, ordered because it was (a) cheap-ish; (b) had a Realtek chip; and (c) had the all-important half-height bracket. It fitted in the Microserver all right, but refused to act on a WOL, at least to begin with…

It turns out there was a little bug-ette in the driver code (prior to 8.3 or 9.1), spotted and fixed by the maintainer about a year ago. If you want to fix it yourself the patch is here. I decided I might as well use the latest drivers rather than re-working those shipped with 8.2, so pulled them, compiled a new if_re.ko and copied it to /boot/kernel in place of the old one. It didn’t work. Ha! Was I naive!

Further investigation revealed that it was completely ignoring this kernel module, as it was using a driver compiled in to the kernel directly. There was no point having the module there, all it does is trick you in to believing that it’s installed. I only realised “my” mistake when, to my astonishment, removing the file completely didn’t disable the network interface. I solved the problem by compiling a new kernel with the built-in Realtek driver commented out, and I’m currently loading the new driver specifically in loader.conf. It works a treat. I could have changed the kernel Realtek driver, but while it’s under review it’s easier to have it loaded separately. Incidentally, the driver is for 9.1 onwards but it works fine on 9.0 so far.

The next task is to fix the Broadcom driver so it works. I may be gone some time…

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