On Sun, 12 Aug 2007, Tom "spot" Callaway wrote:
On Sun, 2007-08-12 at 20:23 +0100, Chris Newport wrote:
Last Solaris support for sun4d was Solaris 2.8 so all of the code will
be there in 2.6 somewhere. Maybe it is just a special case within sun4m
with a few extra drivers, or maybe the code has not been released.
The SS1000 is frustratingly similar to the SS20, most of the devices are
common.
ISTR that Sun4d was a joint venture with Cray, so some code might
be encumbered. I have not seen code so I can only guess.
I hate to be a bother here, but aren't there some legal concerns with
looking at Solaris source code, then implementing code in Linux?
Even on OpenSolaris, there is a grey area as to whether one can legally
view CDDL licensed code, then reimplement it as GPL (CDDL is
GPL-Incompatible) for Linux... but on old Solaris, that code should be
proprietary, unless Sun opened it when I wasn't looking.
I do not know how much (if any) old solaris code was officially released.
I just did a search on the web for the SunMMU as Sun don't apear to have
any usefull documentation available (there was more when they supported
sun4c) and LSI apear to have lost all their documentation on the chips
used in my SS1/SS2.
Mark, can you legally be doing this?
There are serveral points to make at this point.
1) I have not changed any Linux code based on Solaris or OpenSolaris
source code, so no copyright issues there.
2) As I understand the numerous documents on the Sun web site, Sun do not
support sun4c, sun4d or Sun4m so it is posible to argue that copyright is
not very relevent to the architecture specific elements relating to these
hardware architectures. They do not exist in OpenSolaris code anyway.
Lawers may disagree :).
3) What I have been doing for sun4c is to compare what Linux is doing with
what is going on in the Solaris/SunOS code in order to see if they shead
light on why verious scenirious in Linux behave badly. So far all I have
rearly managed to confirm is that the vast magority of the Linux low level
code for sun4c is functionaly identical to Solaris/SunOS. I have not
managed to explain why Linux fails in the verious ways it does and the
Solaris Source code has not helped. I may be wrong but I can't see any
copyright issues with doing this comparison.
4) There can't be any copyright against writing values into the sun4c MMU
PTE registers/memory and reading values back to see what they contain.
With the SunMMU.txt file, all I have done is merge the information from
Linux source code. and the tests I have done, to provide a document that
matches what I have found. This has then been checked to see if it is
consistant with what is indicated in the Solaris code. Where there are
some grey areas (where code operation is consistant but not identical) I
have made a note to indicate that what is documented may not be correct
or may vary from system to system. Is there an issue with this?
Regards
Mark.
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