Bug#72479: Further details on Data Access Exception

[Alan Bain <A.F.R.Bain@statslab.cam.ac.uk>]

To test the theory of memory locations I borrowed some more
RAM.  I can confirm that in a Sun IPX the following memory
configurations work


Bank 0   16Mb   16Mb   16Mb
     1   16Mb   4Mb    16Mb
     2          4Mb     4Mb
     3          4Mb     4Mb


And that the following DOES NOT work


Bank 0    4Mb
     1    4Mb
     2    4Mb
     3    4Mb

[Gives Data Access Exception on loading Ramdisk]


My other problem turns out to be that the Sun has two framebuffers,
an onboard CG6 (which developed a fault) and a CG3 in an SBUS slot.
Bootwas from this second CG3 in the sbus slot; however I saw nothing
because all the linux kernel output was on the CG6 on the M/B.

At the very least these would be useful FAQ entries!  I have a lot of
machines with two framebuffers, usually IPCs which has a colour CG3
added to supersede the on board BW2.  I suspect this could show the
same trouble.


Incidentally the IPC memory is configured as 3 banks of 4Mb and this
generates the same problem.


Alan Bain