ok I may be using it wrongly with 64bit but it works flawlessly witth 32bit big and little endian. however it MAY be a perl bug considering the 'ioctl' command not the packing itself.

ad A) it works ;-)
ad B) I know that, but I had more problems with that than without
I'm using:

my $BIG_ENDIAN = unpack("h*", pack("s", 1)) =~ /01/;

if($BIG_ENDIAN) {
  print STDERR "[big endian]\n" if $debug;
} else {
  print STDERR "[little endian]\n" if $debug;
}
[download]

never failed so far.
Thanks for the pointer to perlpacktut, I'll try a bit more before mailing anyone. But I definitely don't see why 64bit should not work like 32bit in this regard. Maybe I'm doing it wrong all the time, and it works on 32bit big/little endian by chance. Well I don't think that either ;-)

Thanks!