Bug#923675: Add related bug #916690 info

[Petter Reinholdtsen <pere@hungry.com>]

Debian Edu ran into this problem when installing Kerberos as a server from d-i, 
and solved it by running a process in the background to monitor the entropy level, 
and when it was running low, it would flush the file buffers and run 'find 
/target' to force some IO operations that would add entropy to the kernel.

The code can be found in
<URL: https://salsa.debian.org/debian-edu/debian-edu-config/blob/master/share/debian-edu-config/d-i/finish-install >
and look like this:


# Try to add entropy when running low
(
   cd /
   while true ; do
       entropy="$(cat /proc/sys/kernel/random/entropy_avail)"
       if [ 130 -gt "$entropy" ] ; then
           log "low on entropy, pool is $entropy. trying to add more"
           # Disk IO add entropy to the kernel.  Flush cache to ensure find and 
           # touch/rm causes disk IO.
           sync
           echo 3 > /proc/sys/vm/drop_caches
           find /target > /dev/null || true
           touch /target/var/tmp/foo
           sync
           rm /target/var/tmp/foo
           sync
           entropy="$(cat /proc/sys/kernel/random/entropy_avail)"
           log "entropy pool is $entropy after trying to add"
       fi
       sleep 20
   done ) < /dev/null 2>&1 3>/dev/null 4>&3 5>&3 6>&3 | logger -t edu-entropy-add 
& epid=$!

... install stuff ...

# Ignore errors in case the entropy gathering is no longer running
if kill $epid ; then
    :
else
    log "error: killing the entropy gathering job failed - exited?"
fi

Perhaps a similar approach could be inserted into the default Debian Installer?

-- 
Happy hacking
Petter Reinholdtsen