After migration from 2.6.18-6-amd64, a newly installed kernel 2.6.26-2-amd64 failed to load:

[ 2.871916] Broadcom NetXtreme II Gigabit Ethernet Driver bnx2 v1.7.5 (April 29, 2008)
...
[ 3.631838] firmware: requesting bnx2-06-4.0.5.fw
...
[ 105.599417] bnx2: Can't load firmware file bnx2-06-4.0.5.fw
...
[ 105.599563] bnx2: probe of 0000:03:00.0 failed with error -2
...
[ 106.791394] firmware: requesting bnx2-06-4.0.5.fw
[ 203.699607] bnx2: Can't load firmware file bnx2-06-4.0.5.fw
...
[ 203.699742] bnx2: probe of 0000:05:00.0 failed with error -2

First of all, firmware is in non-free branch, so /etc/apt/sources.list must contain “non-free” repository and:
install firmware-bnx2 package:

apt-get install firmware-bnx2

;

double check the files in /lib/firmware/;

Some people report it’s still impossible to load firmware from initrd, so you may wish to remove bnx2 line from ‘/etc/initramfs-tools/modules’;

“firmware-bnx2” already has initrd update scripts, but you may want to re-check the created image.
You can extract the initrd image using

gzip -dc /boot/initrd.img-[]kernel version-arch] | cpio -id

Cross your fingers;
telinit 6;
It just worked for me:

# uname -a
Linux … 2.6.26-2-amd64 #1 SMP … x86_64 GNU/Linux

Still got no ping? Login to console and rmmod bnx2 && modprobe bnx2 ­čÖü