Xenix FS history lesson please

[Madison Kelly]

D. Hugh Redelmeier wrote:
> | From: Madison Kelly <linux-5ZoueyuiTZhBDgjK7y7TUQ at public.gmane.org>
> 
> |  However, I am having next to no
> | luck finding information on, or the differences between, the Xenix '/root' and
> | '/usr' filesystems. I even looked up the old Xenix programming manual (closest
> | I could find to a sysadmin doc) from 1979, but could not find the differences.
> | 
> | Anyone here remember anything about those filesystems? (IDs 02h [Xenix /root]
> | and 03h [Xenix /usr])
> 
> The Wikipedia article on Xenix gives some hints.  It suggests that Xenix
> didn't hit the IBM PC until 1983.  That is when it would have started
> to use the IBM PC partitioning scheme.
> 
> I have an earlier machine that runs Xenix.  Partitioning was not at
> all like IBM PC partitioning.
> 
> Those filesystems are probably just Seventh Edition or System III
> filesystems (I don't remember if those are different).
> 
> I don't know why the IDs are distinct.  Possibly just so that the
> kernel can more easily find the partition it needs to get started
> (root's).
> 
> Those IDs might have been assigned later.  I don't know what filesystems 
> Xenix used later.

Thanks for the reply!

   A friend (off list) dug the following up:

     *  512MB max size limit
     * 1024 byte blocks, 64 byte inodes, fixed at 16 inodes per block
     * very similar to SysV file system (which is also very similar to 
Coherent, Minix, and other older FSs)
     * very limited support on linux, provided by 'sysv' FS driver
     * linux does not understand 'divvy' slices (same concept as BSD 
slicing up a partition into slices), only the actual FS data itself
     * partition type 0x2 and 0x3 are the same actual FS on disk
     * type 0x3 was previously used for /usr (for some reason) but it 
was deprecated and all Xenix FSs should "now" use 0x2

   For my purposes, and at this point in the program's development, 
that's all I really need. Though, I'd love to expand what I know of it, 
as information trickles in. I'm trying to get something of a wiki going 
to cover all the different partition types and file systems.

http://wiki.tle-bu.org/index.php/Supported_Filesystems

   Should you happen to come across anything more, please let me know!

Madi
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