X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?p=rpikern;a=blobdiff_plain;f=doc%2Fnotes.md;fp=doc%2Fnotes.md;h=30dc0508af3dabef009080300bdef84f3ce53dbc;hp=5a372d8dc344fc148c63871e1c4fa8e1df4b2211;hb=574147e84aafb61db3cf8b595d2a12ce5ba160de;hpb=99bdc8838f189f79ba77bfbbf41d7f1b4839ce0f

diff --git a/doc/notes.md b/doc/notes.md
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--- a/doc/notes.md
+++ b/doc/notes.md
@@ -1,5 +1,8 @@
 Raspberry Pi2 notes
 ===================
+
+Memory access ordering
+----------------------
 Accessing different peripherals migh return results out of order. See bcm2835
 spec section 1.3. Use memory barriers as follows:
  - place write barrier before the first write to a peripheral
@@ -10,6 +13,12 @@ Multiple accesses to the same peripheral in a row do not require barriers.
 Interrupt handlers should have a read barrier before their first read, and end
 with a write barrier.
 
+Cache coherency
+---------------
+Two types of cache management:
+ - cache cleaning (write-back caches)
+ - cache invalidation (all caches)
+
 Cache clean and invalidate operations are also needed before the GPU can see our
 command buffers... see:
 https://github.com/rsta2/uspi/blob/38eaff4f715643a9/lib/synchronize.c