/usr/lib/dracut/modules.d/95nbd/parse-nbdroot.sh is in dracut-network 040+1-1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 | #!/bin/sh
#
# Preferred format:
# root=nbd:srv:port[:fstype[:rootflags[:nbdopts]]]
# [root=*] netroot=nbd:srv:port[:fstype[:rootflags[:nbdopts]]]
#
# nbdopts is a comma separated list of options to give to nbd-client
#
# root= takes precedence over netroot= if root=nbd[...]
#
# Sadly there's no easy way to split ':' separated lines into variables
netroot_to_var() {
local v=${1}:
set --
while [ -n "$v" ]; do
set -- "$@" "${v%%:*}"
v=${v#*:}
done
unset server port
server=$2; port=$3;
}
# This script is sourced, so root should be set. But let's be paranoid
[ -z "$root" ] && root=$(getarg root=)
if [ -z "$netroot" ]; then
for netroot in $(getargs netroot=); do
[ "${netroot%%:*}" = "nbd" ] && break
done
[ "${netroot%%:*}" = "nbd" ] || unset netroot
fi
# Root takes precedence over netroot
if [ "${root%%:*}" = "nbd" ] ; then
if [ -n "$netroot" ] ; then
warn "root takes precedence over netroot. Ignoring netroot"
fi
netroot=$root
unset root
fi
# If it's not nbd we don't continue
[ "${netroot%%:*}" = "nbd" ] || return
# Check required arguments
netroot_to_var $netroot
[ -z "$server" ] && die "Argument server for nbdroot is missing"
[ -z "$port" ] && die "Argument port for nbdroot is missing"
# NBD actually supported?
incol2 /proc/devices nbd || modprobe nbd || die "nbdroot requested but kernel/initrd does not support nbd"
# Done, all good!
rootok=1
# Shut up init error check
if [ -z "$root" ]; then
root=block:/dev/root
wait_for_dev -n /dev/root
fi
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