Hello,
i tried to install NetBSD1.2-sparc-release under sunos4.1.3
and after booting it fsck'ed my /usr-partition (which is
shared between sunos4 and netbsd) and messed it up :-(

under sunos4 i have the following informations:
ickis:[~]:mount 
/dev/sd0a on / type 4.2 (rw)
/dev/sd0g on /usr type 4.2 (rw)
/dev/sd0d on /netbsdroot type 4.2 (rw)

ickis:[~]:dumpfs /dev/sd0g
magic   11954   format  dynamic time    Sun Dec  1 01:22:33 1996
nbfree  19798   ndir    2640    nifree  393965  nffree  14621
ncg     229     ncyl    3650    size    934304  blocks  875660
bsize   8192    shift   13      mask    0xffffe000
fsize   1024    shift   10      mask    0xfffffc00
frag    8       shift   3       fsbtodb 1
minfree 1%      optim   space   maxcontig 1     maxbpg  2048
rotdelay 4ms    rps     60
ntrak   16      nsect   32      npsect  32      spc     512
trackskew 0     interleave 1
cpg     16      bpg     512     fpg     4096    ipg     1920
nindir  2048    inopb   64      nspf    2
sblkno  16      cblkno  24      iblkno  32      dblkno  272
sbsize  2048    cgsize  2048    cgoffset 16     cgmask  0xfffffff0
csaddr  272     cssize  4096    shift   9       mask    0xfffffe00
cgrotor 125     fmod    0       ronly   0
clean   2 (stable)      state   0x4985cd6f (FSOKAY)
blocks available in each of 8 rotational positions
...

Anyone knows what/why/how to get it working ?