trace: remove the TraceEventID and TraceEventVCPUID enums

The TraceEventID and TraceEventVCPUID enums constants are
no longer actually used for anything critical.

The TRACE_EVENT_COUNT limit is used to determine the size
of the TraceEvents array, and can be removed if we just
NULL terminate the array instead.

The TRACE_VCPU_EVENT_COUNT limit is used as a magic value
for marking non-vCPU events, and also for declaring the
size of the trace dstate mask in the CPUState struct.
The former usage can be replaced by a dedicated constant
TRACE_EVENT_VCPU_NONE, defined as (uint32_t)-1. For the
latter usage, we can simply define a constant for the
number of VCPUs, avoiding the need for the full enum.

The only other usages of the enum values can be replaced
by accesing the id/vcpu_id fields via the named TraceEvent
structs.

Reviewed-by: LluĂ­s Vilanova <vilanova@ac.upc.edu>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 1475588159-30598-11-git-send-email-berrange@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/trace/simple.c b/trace/simple.c
index 2f09daf..2ec32e1 100644
--- a/trace/simple.c
+++ b/trace/simple.c
@@ -17,8 +17,8 @@
 #include "trace/control.h"
 #include "trace/simple.h"
 
-/** Trace file header event ID */
-#define HEADER_EVENT_ID (~(uint64_t)0) /* avoids conflicting with TraceEventIDs */
+/** Trace file header event ID, picked to avoid conflict with real event IDs */
+#define HEADER_EVENT_ID (~(uint64_t)0)
 
 /** Trace file magic number */
 #define HEADER_MAGIC 0xf2b177cb0aa429b4ULL
@@ -58,7 +58,7 @@
 
 /* * Trace buffer entry */
 typedef struct {
-    uint64_t event; /*   TraceEventID */
+    uint64_t event; /* event ID value */
     uint64_t timestamp_ns;
     uint32_t length;   /*    in bytes */
     uint32_t pid;
@@ -202,7 +202,7 @@
     rec->rec_off = write_to_buffer(rec->rec_off, (void*)s, slen);
 }
 
-int trace_record_start(TraceBufferRecord *rec, TraceEventID event, size_t datasize)
+int trace_record_start(TraceBufferRecord *rec, uint32_t event, size_t datasize)
 {
     unsigned int idx, rec_off, old_idx, new_idx;
     uint32_t rec_len = sizeof(TraceRecord) + datasize;