I've spent this afternoon trying to bring some old (P1 and P2 build)
Loon 3 boards back from the dead (or at least dormant), and have had
much confusion about which RAM banks are fitted with which chips, how
they've been modded, and whether I should be using small or large memory
model.

In order to help sort out the mess, I've added a little memory probing
thingy to bootldr which displays, once the memory is initalised, what it
can find. For example, on a P2 board with small memory model:

Small memory model selected, bank size 64Mbytes
Bank 0:
A0000000-A3FFFFFC (64Mbytes)
Bank 1:
A4000000-A7FFFFFC (64Mbytes)
Bank 2:
AC000000: no RAM found
Bank 3:
A8000000: no RAM found

or on an E1 board with large memory model:

Large memory model selected, bank size 256Mbytes
Bank 0:
A0000000-A7FFFFFC (128Mbytes) not contiguous
Bank 1:
B0000000-B7FFFFFC (128Mbytes) not contiguous
Bank 2:
90000000: no RAM found
Bank 3:
80000000-87FFFFFC (128Mbytes) not contiguous

This is all checked into subversion though not tagged as yet.

Now, if only bootldr could detect the type of RAM chip and set up the
memory controller appropriately so one bootldr works on both types of
board...

Chris
-- 
Chris Jones - chris@martin-jones.com
Martin-Jones Technology Ltd, makers of Solidlights
148 Catharine Street, Cambridge, CB1 3AR, UK
Phone +44 (0) 1223 655611 Fax +44 (0) 870 112 3908
http://www.solidlights.co.uk/