Jim's Depository

The following modules need to be added to the Debian init ramdisk to support root on a 9p disk:

./kernel/fs/9p/9p.ko
./kernel/net/9p/9pnet.ko
./kernel/net/9p/9pnet_rdma.ko
./kernel/net/9p/9pnet_virtio.ko

To add these modules, you will extract an init ramdisk (which is just a compressed cpio archive), add the files, and run a depmod -a in it. Then re-archive it.

The commands I used to make mine are:

#!/bin/sh

set -e

mkdir /tmp/9p-ramdisk
cd /tmp/9p-ramdisk
zcat /boot/initrd.img-3.16.0-4-amd64 | cpio -id

mkdir lib/modules/3.16.0-4-amd64/kernel/fs/9p
mkdir lib/modules/3.16.0-4-amd64/kernel/net/9p

cp /lib/modules/3.16.0-4-amd64/kernel/fs/9p/9p.ko lib/modules/3.16.0-4-amd64/kernel/fs/9p/9p.ko 
cp /lib/modules/3.16.0-4-amd64/kernel/net/9p/9pnet.ko lib/modules/3.16.0-4-amd64/kernel/net/9p/9pnet.ko 
cp /lib/modules/3.16.0-4-amd64/kernel/net/9p/9pnet_rdma.ko lib/modules/3.16.0-4-amd64/kernel/net/9p/9pnet_rdma.ko 
cp /lib/modules/3.16.0-4-amd64/kernel/net/9p/9pnet_virtio.ko lib/modules/3.16.0-4-amd64/kernel/net/9p/9pnet_virtio.ko 

depmod -b /tmp/9p-ramdisk

find . | cpio -o -H newc | gzip > /boot/initrd.img-3.16.0-4-amd64-9p

Update: This works, but seems to be a bad idea. When I try to do aptitude update it fails with lines like this…

E: Unable to determine file size for fd 7 - fstat (2: No such file or directory)
E: Problem opening /var/lib/apt/lists/ftp.debian.org_debian_dists_jessie_contrib_binary-amd64_Packages
E: The package lists or status file could not be parsed or opened.
E: Unable to determine file size for fd 8 - fstat (2: No such file or directory)
E: Problem opening /var/lib/apt/lists/ftp.debian.org_debian_dists_jessie_contrib_binary-amd64_Packages
E: The package lists or status file could not be parsed or opened.

… which seems to say that 9p has a problem with some operation aptitude needs.

Back to disk images for me.