PL3 description

[Stephen Henson (CSM) <shenson@camborne-school-of-mines.ac.uk>]

Right, this machine is allowing me to send some mail for the moment so I'll see
how long my luck lasts :-)

PL3 will follow soon. I've had to do all manner of horrible things to get this
going. The main addition to this patch level is a bypass to the lrecno bug.
If your hard disk software is XHDI compliant then there are no problems.If
not then if the 'huge' partition is one of the first sixteen bios drives
(corresponding to letters A-P inclusive) *and* your software is either ICD
or some AHDI variant then you should also be OK.

	ICD software has a few caveats. The pun_info structure is different
for ICD and I can't find any more info about it so I've 'estimated' what the
precise form of it is; this seems OK up to 6.06 but I can't guarantee anything.
ICD software has an appalling bug (other than the stupid lrecno bug that occurs
in almost all ST hard disk software) which screws up when trying to read/write
physical mode with the cache on. Basically if you need to use huge partitions
with ICD software then you'll have to turn the cache off.

	I've tried to use all possible means to access partitions and to bypass
the stupid bugs. The current version uses no less than 5 different methods to
access partitions!

	A warning is in order here. These weird and wonderful new access methods
only come into play when really needed; that is if partitions are created that
are bigger than 64Mb (and necessarily V2). In my limited experience so far these
methods (whilst perfectly legitimate) use poorly tested features of hard disk
software so BE CAREFUL!!!!

	OK enough waffle; if you want to create a huge partition then 'minit -V'
should now handle things automagically. The restriction that the sector size
should be 1K or 512 bytes is now removed (it will be bigger than 1K anyway for
huge partitions). 'minit -t' has been altered somewhat: it tests several things
now and also goes through most of  the steps to create the filesystem, without
actually writing anything.

	Quick note about 'minit'. It needs a bit of an overhaul in the
protection department (keeping TOS away from the partitions without MiNT
running). I'll see if I can work out some semi-foolproof method for later
versions; this really is a complete pain to do and shouldn't be needed :-(

	fsck should also work now on huge partitions.

	I'd be most grateful if someone would test out huge partitions. A good
FS workout would be:

	1. create with minit -V.
	2. Fill up the filesystem to bursting point.
	3. Run fsck at regular intervals.

	I could really do with this feature being checked before release. There
could easily be some bug lurking (particularly in fsck) which only rears it's
ugly head when huge partitions are accessed.

	A few other random musings: other stuff has been added to this patch
level, primarily to support a binary configuration program that is currently
'under construction' (I hope to send this out soon, possibly with pl4) and a 
couple of minor bugs have been fixed.

Have fun, Steve.

PS In case you haven't realised by now: pl3 is a *big* patch :-)