In my little program (rpi_stub) it's time to turn on MMU and caches.
Most of it I seem to have hold of, except cache invalidations.
In multicore situation (rpi_doesn't support yet, but maybe later), what needs to be invalidated and how?
I understand I-cache, D-cache, L2-cache, branch predictor, I-TLB, D-TLB, but what else?
And to which depth? I understand that the I-cache can't be invalidated further than PoU - but is it enough?
There is an invalidation command for D-cache line upto PoC. (I understand D-cache has to be invalidated line-by-line.)
And do they all need to be invalidated separately, or does, say, D-cache invalidation invalidate L2 too?
Is there a common TLB-invalidation?
And where to find the info in the documents? There are some "implementation dependent" stuff (like bits) in the architecture manual, but Cortex-A7 MPCore TRM doesn't mention anything about some stuff.
(An example: bit 9 of 1st level translation table entries.)
In the architecture manual, the list of cache maintenance operations give links to operation description, and that description repeats the (rough) function description and gives a link back to the list.
Where to find the contents of the register to read/write from/to the CP15?
Also, is there any example code around?
Aah, even if search didn't find anything relevant, when I created this question, there appeared a couple of discussions under the "MORE LIKE THIS", and I found answers in a comment
A new problem emerged, though: I don't seem to be able to figure out the parameter to DCCSW.
I found the description on page B4-1745 in "ARM Architecture Reference Manual, ARMv7-A and ARMv7-R edition", issue C,
but I can't make sense of it. What are the field lengths?
I found a a code in the web that helped me to figure the parameter fields out.
It was hard to believe that bit fields of one register depend on bit field values of another register!
Now the caches and MMU are enabled, and the program still works
(almost - but that's a different story).
I wanted to mark this question solved, but I guess you can't mark a posting in another thread as a solution(?).
(It's a bit embarrassing to mark my own posting, though...)
Hi turboscrew
I'm afraid you can't mark a post in another thread as a solution, no. Thanks for enduring the embarrassment, although I often find I get the best answers when I talk to myself
The right way to do it, is exactly like you did:
Create your own answer with a link to the answer that solved the problem, then mark your own answer "Correct".
Doing this definitely deserves the earned points.
Marking an answer correct also closes the question, thus it's easier for "open-question-hunters" to find those questions that have not been answered yet.