My ethernet card is a Realtek RT8168 running on the r8169 driver module. I noticed an error in dmesg complaining about absent firmware, but the card seemed to work perfectly well without it in both Slackware and LFS.

I found the specified firmware file inside a Debian non-free package, so I extracted it and put it in /lib/firmware. Now I don't get that error any more, but I haven't noticed any difference in the card's behaviour. So what is the firmware for? Is it anything to do with this article which suggests that the kernel's r8169 driver is (or once was) unstable on RT8168 chips? Of course the article could be way out of date; I couldn't find a date on the page.

Just curious

PS: Someone else had the same problem (https://www.linuxquestions.org/quest...2-a-4175555113) but in Debian itself. They don't say though whether their card worked without the firmware.

yes, they are "almost" the same. But better to use the perfect one. The other one is not fully compatible, there can be packet loss, speed problems and other interesting effects. At least something similar happened to me. (I have an r8169 chip and initially the kernel loaded r8168). But I don't fully understand it (too).

my r8169 will cause some kernel versions to panic without the firmware and have to blacklist the module at grub prompt when booting some installation iso's

My Slackware kernel (4.4.14) doesn't have an r8168 module, only r8139 and r8169. The article I tagged tells you how to build the proprietary driver instead. But the symptoms described (slowness in downloading pages, with transfer speeds dropping to a few hundred kB/sec) didn't show up on my machine. On the contrary. It was my old machine, which used an Intel card, that did that, at least when I was using scp. I noticed the difference when I did my first dumps from the new machine. Instead of variable speeds that sometimes dropped to 400-600 kB/sec, I now have a steady transfer speed of 1.4 MB/sec. And that was without the firmware.

Funny. I thought I had an r8169 too, little used but no issues. For a prolific designing company with multiple kernel drivers like Realtek, the kernel documentation is zero. From /usr/src/linux-<blah>/drivers/net/ethernet/realtek/r8169.c
So we end up that the r8169 module doesn't provide firmware for the 8169, if such a thing exists
I tried with 'lspci-vv' but the best ID I got was 8111/8168/8411, and this info on pci id 10ec:8168 . There's just versions of 8168 in the firmware.
The principal difference appears to be what version of pcie bus they support. All the main features are identical. And some geek in Realtek is throwing around device numbers like confetti at a wedding.

Now, vaguely thinking back to the 2012 blurb when buying this box, I vaguely remember an 8111 nic in the specs, and surprise that an 8111 chip/ip core was supported by an 8169 module. Isn't memory a funny thing?

So my (IIRC) RTL8111 is actually an 8168 in an earlier phase using the 8169 module. And we along with 8411 owners all have pretty identical RTL8168 devices with the same feature set, just running on different pcie bus specs.

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Now that is interesting! So are these firmware patches just modifying the card's use of the pci bus?

That was my cursory assessment of it. Realtek's info is poor. But there was PCIe-1.0 - 5.x so far.

There's powerful incentives on hardware manufacturers not to fiddle with designs which are tested, approved, & happy in their nappies/diapers. Any messing would require retesting, delays, expense, etc. They could test it at the max performance exceeding PCIe-1.0. If they have the heart of a device which works, they might accommodate the extra instructions or speed in firmware. It's certainly what I'd try to do. I'm sure there are more sales in IP Cores than silicon these days anyhow.

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Well, that's the solution then. Thanks, business_kid.

Yeah. That way they just add a different prescaling divider for the clock and fiddle with the number;maybe add 1 or 2 extra commands from the new spec to ignore

EDIT: Just for the record, with the firmware there in /lib/firmware/rtl_nic/ my rtl8111(iirc) doesn't ask for any, or load any. Evidently it's preloaded with something.