Comment 90 for bug 285392

Hi there! I also had this bug in all modern distros including *ubuntu. It doesn't interfere with anything, but it's very annoying during silent boot mode. Now i'm using Gentoo, which has manual kernel configuring by default. I also had this warning here, but it wasn't so flaring during verbose boot. I find option in kernel config, which is responsible for this stuff, i disabled it, and now everything is okay ;-)
You can find it in : Device Drivers -> Serial ATA (prod) and Parallel ATA (experimental) drivers -> SATA Port Multiplier support. If it's possible for you in *ubuntu to recompile your kernel, then you can do this. It's not an advertising of Gentoo of course. :-)

Here is screenshot from menuconfig.