> ok to do that.
>
> At boot, NetBSD report he found the drive but "could not sense mode 4/5" and
> "using a fictitious geometry".
>
> I've 'low?' formatted one and now it report himself as a 387Mb
> 512bytes/sector, but should be 400Mb in 512b/s and 406Mb in 520b/s... (from
> datasheet)
> ...then I suspect I've just formated it in 512b/s under a 520b/s low format
> ? :-/


are you sure it's 400MB or 400*10^6 bytes?
400*10^6 bytes will be about 387.

>
> Is there a possibility to say disklabel use a 520b/s geometry by entering
> all drive parameters by hand or must tweak sd.c and other SCSI or what ever
> drivers ?

you must write your own program sending raw scsi commands to read the
contents. NetBSD can't handle sector sized != 512 now and for sure won't
ever handle non power-of-two sizes.