I have in /etc/fstab of my pxe client:
tmpfs /tmp tmpfs rw,mode=1777,size=128m 0 0
tmpfs /var/run tmpfs rw,mode=0755,size=20m 0 0
The second only to avoid booting errors due to locking.
But the small /tmp breaks pkg. I had to run:
mkdir /var/tmp/pkgtmp
env...