Subject: Re: newfs_msdos
To: None <>
From: Brook Milligan <>
List: tech-userlevel
Date: 12/10/1999 08:15:43
   On Thu, Dec 09, 1999 at 10:57:24PM -0700, Brook Milligan wrote:
   > Clearly, no one feels like writing unnecessary config entries.  The
   > information (which includes more than geometry) needs to come from
   > somewhere, though.

   Which informations ? How can mformat work then ?

Well, information like sectors per cluster, a drive number, number of
root directory entries, ... .  Perhaps you used command line swithces
for mformat to set these?  Perhaps the data come from within the
program as compiled in defaults?  I don't know exactly how you
manipulated mformat.  The point is that the BIOS parameter block needs
stuff besides the geometry; see any technical document that describes
the layout of a MS-DOS bootsector.  Command line switches could be
given to set these, but it also seems reasonable to include this in
whatever table describes the floppy parameters (compiled in or

A compiled in table will certainly work, but allows for no extensions
except by recompiling.  Use of /etc/floppytab allows for extensions to
new types of disks.  That seems preferable to me, since it "makes
sense" (to me, anyway; in essense we are talking about parameters
describing floppies after all), it does not interfere with the only
other program that uses that file, it allows for greater flexibility,
and we have the file anyway for only a slightly different purpose.

   > - the BSD disklabel (this may not exist on all disks needing
   >   formating, or is it true that the DIOCGDINFO ioctl(2) will always
   >   yield useful geometry information about any raw disk device? is that
   >   geometry the BIOS geometry? if not, how is that retrieved?)

   I'm sure all the infos are here (we tell to tell fdisk the geometry,
   and can print it back when re-reading the partition table). 
   The table would still be needed for floppies though ...

Yes, it is a good idea to try reading the disklabel as a means of
getting whatever information is available.

Overall, I'm unclear about your message.  Is it that there is no need
for an enhanced newfs_msdos?  Is it that /etc/floppytab should not be
used as a table to contain the information needed?  Is it that this is
a good idea but you'd like to see information in the disklabel used if
possible?  Or is it something else?  There is no point in continuing
if the message is the first?  I'm asking these questions, after all,
so that the final version will be accepted into the tree.