Clarify alignment requirements

Signed-off-by: Christian Babeux <christian.babeux@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/common-trace-format-specification.txt b/common-trace-format-specification.txt
index 23243894d4da5773ee6acf5717117c975475236d..482731c08c551319f0c039621dcc63f5ef49bc5d 100644 (file)
--- a/common-trace-format-specification.txt
+++ b/common-trace-format-specification.txt
@@ -165,6 +165,11 @@ by default. It is however recommended to always specify the alignment
 explicitly. Alignment values must be power of two. Compound types are
 aligned as specified in their individual specification.
 
 explicitly. Alignment values must be power of two. Compound types are
 aligned as specified in their individual specification.
 

+The base offset used for field alignment is the start of the packet
+containing the field. For instance, a field aligned on 32-bit needs to
+be at an offset multiple of 32-bit from the start of the packet that
+contains it.
+

 TSDL meta-data attribute representation of a specific alignment:
 
   align = value;                                /* value in bits */
 TSDL meta-data attribute representation of a specific alignment:
 
   align = value;                                /* value in bits */


@@ -682,8 +687,7 @@ Strings are always aligned on byte size.
 The event packet header consists of two parts: the "event packet header"
 is the same for all streams of a trace. The second part, the "event
 packet context", is described on a per-stream basis. Both are described
 The event packet header consists of two parts: the "event packet header"
 is the same for all streams of a trace. The second part, the "event
 packet context", is described on a per-stream basis. Both are described

-in the TSDL meta-data. The packets are aligned on architecture-page-sized
-addresses.
+in the TSDL meta-data.

 
 Event packet header (all fields are optional, specified by TSDL meta-data):
 
 
 Event packet header (all fields are optional, specified by TSDL meta-data):