Nonfree firmware in initrd?

[Matthew Pounsett]

I'm having some issues getting FAI to boot Debian Buster on an old
Dell PowerEdge R210 II with Broadcom NetXTreme II interfaces.  The
interfaces need the bnx2 (nonfree) drivers, which I have in my
nfsroot, but I don't think they're getting included in the initrd.

The necessary driver is present:
-rw-r--r-- 1 root root 103904 Aug 23 2019
nfsroot/usr/lib/firmware/bnx2/bnx2-mips-09-6.2.1b.fw

When the kernel goes to load the driver, it's failing with an "error
-2".  The only references I can find to this during firmware load are
suggestions that the driver file isn't found.   Once the boot
completely fails and I end up at the initrd's emergency shell, this is
what I can get from dmesg (re-typed by hand due to crappy Java
console):

bnx2: QLogic bnx2 Gigabit Ethernet Driver v2.2.2.6 (January 29, 2014)
bnx2 0000:01:00.0 eth0: Broadcom NetXtreme II BCM5716 1000Base-T(C0)
PCI Express found at mem c0000000, IRQ 16, node addr d4:ae:52:cd:08:19
bnx2 0000:01:00.1 eth1: Broadcom NetXtreme II BCM5716 1000Base-T(C0)
PCI Express found at mem c0000000, IRQ 17, node addr d4:ae:52:cd:08:1a
bnx2 0000:01:00.0: firmware: failed to load bnx2/bnx2-mips-09-6.2.1b.fw (-2)
bnx2 0000:01:00.0: Direct firmware load for
bnx2/bnx2-mips-09-6.2.1b.fw failed with error -2

There's a screencap of the original text here:
<https://www.dropbox.com/s/ubotjx3rngrsi5c/dracut-bnx.jpg?dl=0>

Looking in /usr/lib in the emergency shell I do not find
/usr/lib/firmware at all.

I've added the drivers to the dracut config in nfsroot, just in case:
% cat nfsroot/etc/dracut.conf.d/50-bnx2.conf
add_drivers+="bnx2"

The following block appears in my /etc/fai/NFSROOT file (indented here
for readability):
   PACKAGES install-norec NONFREE
   firmware-bnx2 firmware-bnx2x firmware-realtek
   firmware-cavium
   firmware-misc-nonfree

And I'm invoking fai-make-nfsroot as:
# fai-make-nfsroot -kv -c NONFREE

After running fai-make-nfsroot, it looks to me like the initrd image
isn't being updated.
-rw-r--r-- 1 root root 38329616 Mar  5 17:12
/opt/tftp/fai/initrd.img-4.19.0-14-amd64

Am I missing a step somewhere?