Not Supported dos not mean it can be done.
Downloading the large sysrcd.dat to the computers memory (tmpfs) is not always the luxury available on all those sick computers.
Iif you looking for a non-supported feature like share sysrcd.dat though nfs and you have some time to spare there is a way ......
What you need is the nfs kernel modules (nfs.ko nfs_acl.ko,lockd.ko sunrpc.ko ) the portmap binary must be added to the initram.igz (these can found in the squashfs-ed sysrcd.dat)
some lines of code in the init script for loading these modules and mount the nfs share where the sysrcd.dat file is located, next the script continues like sysrcd.dat was downloaded
only 800Kb memory usage on kernel modules en portmap process
the code I used is not very portable, but start looking at the sysreccd_bootstrap_net routine
you will see that is not hard to add a extra type of url....
I don't know if there is more to squeeze on memory consumption. but this was for me the trick. o yah tmpfs default size is half the memory.. -o size=32m is more frendly.
still not convinced? for example started with a healthy 1Gb machine there was only 150Mb of active pages while X is running..... leaving 850MB....
root@sysresccd /root % uname -a
Linux sysresccd 2.6.27.07-std113 #1 SMP Sat Dec 6 00:19:24 UTC 2008 i686 Intel(R) Pentium(R) 4 CPU 3.40GHz GenuineIntel GNU/Linux
root@sysresccd /root % df
Filesystem 1K-blocks Used Available Use% Mounted on
tmpfs 32768 26148 6620 80% /
64657408 4714304 56658624 8% /mnt/cdrom
/dev/loop0 204288 204288 0 100% /mnt/livecd
tmpfs 32768 26148 6620 80% /mnt/memory
udev 10240 172 10068 2% /dev
There was only one trick: add a loopback adapter before start the portmaper like this
ifconfig lo 127.0.0.1 netmask 255.0.0.0 up