dump memory footprint

[Emmanuel Dreyfus <manu%netbsd.org@localhost>]

Hi

I have a problem with dump memeory footprint. I would like to dump
a filesystem containing 34 kB, and dump will not do it unless I setup
around 10 MB of swap:

# ls -loa /flash/                                                              
total 251561
drwxr-xr-x   3 root  wheel  -            512 Mar 21 13:46 .
drwxr-xr-x  18 root  wheel  -            512 Mar 21 13:11 ..
-r--r--r--   1 root  wheel  nodump     75220 Mar 20 14:39 boot
drwxr-xr-x   6 root  wheel  -            512 Mar 21 13:10 etc
-rw-------   1 root  wheel  nodump 117514598 Mar 21 13:28 netbsd
-rw-r--r--   1 root  wheel  nodump  11118529 Mar 21 13:27 netbsd.old.gz
# du -ks /flash/etc/                                                           
34      /flash/etc/
# dump -h0 -0uf /dev/null /flash/ 
  DUMP: Ignoring u flag for subdir dump
  DUMP: Dumping sub files/directories from /flash
  DUMP: Dumping file/directory /flash/
  DUMP: Found /dev/rwd0a on /flash in /etc/fstab
  DUMP: Date of this level 0 dump: Thu Mar 21 13:47:38 2013
  DUMP: Date of last level 0 dump: the epoch
  DUMP: Dumping a subset of /dev/rwd0a (a subset of /flash) to /dev/null
  DUMP: Label: none
UVM: pid 874 (dump), uid 0 killed: out of swap
Killed                                        

It seems rather unreasonable to allocate more than 10 MB just to dump 34 ko;
Are there any relevant options to reduce dump memory footprint?

-- 
Emmanuel Dreyfus
manu%netbsd.org@localhost