X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=libringbuffer%2Fring_buffer_frontend.c;h=b45ec543981c940b7beacce8dbc885625efb9a3a;hb=2432c3c9bdce3c94632f7c619165ab1278a69551;hp=01d0f5e87007c269f15026366a35fc1ae9827e85;hpb=431d5cf0d589654dfa74e07194dd186f5311cc29;p=lttng-ust.git

diff --git a/libringbuffer/ring_buffer_frontend.c b/libringbuffer/ring_buffer_frontend.c
index 01d0f5e8..b45ec543 100644
--- a/libringbuffer/ring_buffer_frontend.c
+++ b/libringbuffer/ring_buffer_frontend.c
@@ -55,6 +55,22 @@
 #define max(a, b)	((a) > (b) ? (a) : (b))
 #endif
 
+/*
+ * Use POSIX SHM: shm_open(3) and shm_unlink(3).
+ * close(2) to close the fd returned by shm_open.
+ * shm_unlink releases the shared memory object name.
+ * ftruncate(2) sets the size of the memory object.
+ * mmap/munmap maps the shared memory obj to a virtual address in the
+ * calling proceess (should be done both in libust and consumer).
+ * See shm_overview(7) for details.
+ * Pass file descriptor returned by shm_open(3) to ltt-sessiond through
+ * a UNIX socket.
+ *
+ * Since we don't need to access the object using its name, we can
+ * immediately shm_unlink(3) it, and only keep the handle with its file
+ * descriptor.
+ */
+
 /*
  * Internal structure representing offsets to use at a sub-buffer switch.
  */