[PATCH]xentrace_format doesn't work on 64 bit arch

[PATCH]xentrace_format doesn't work on 64 bit arch

[Rob Gardner]

The xentrace_format script doesn't work on x86/64. Python pads the input 
structure because the first field is 32 bits and the next is 64 bits, 
whereas x86-32 doesn't pad. The quick fix is to read the cpu id 
separately as a 32bit value, then read the rest of the trace record. 
Here is a little patch that does that. Tested on x86/32 SMP and x86/64.


Signed-off-by: Rob Gardner  <rob.gardner@hp.com>

# HG changeset patch
# User rob.gardner@hp.com
# Node ID a65d04d96b04d686f29c7a0df8c829b46a957d4f
# Parent  9bf6f907b3ff0261902f06d261f76c1bd12af9f5
Change xentrace_format to handle 64 bit structure packing

diff -r 9bf6f907b3ff -r a65d04d96b04 tools/xentrace/xentrace_format
--- a/tools/xentrace/xentrace_format    Wed Nov 16 10:29:52 2005
+++ b/tools/xentrace/xentrace_format    Thu Nov 17 22:28:32 2005
@@ -85,7 +85,9 @@
 
 # structure of trace record + prepended CPU id (as output by xentrace):
 # CPU(I) TSC(Q) EVENT(L) D1(L) D2(L) D3(L) D4(L) D5(L)
-TRCREC = "IQLLLLLL"
+# read CPU id separately to avoid structure packing problems on 64-bit 
arch.
+CPUREC = "I"
+TRCREC = "QLLLLLL"
 
 last_tsc = [0,0,0,0,0,0,0,0]
 
@@ -94,11 +96,16 @@
 while not interrupted:
     try:
     i=i+1
+        line = sys.stdin.read(struct.calcsize(CPUREC))
+        if not line:
+            break
+        cpu = struct.unpack(CPUREC, line)[0]
+
         line = sys.stdin.read(struct.calcsize(TRCREC))
         if not line:
             break
 
-        (cpu, tsc, event, d1, d2, d3, d4, d5) = struct.unpack(TRCREC, line)
+        (tsc, event, d1, d2, d3, d4, d5) = struct.unpack(TRCREC, line)
 
     #tsc = (tscH<<32) | tscL

Re: [PATCH]xentrace_format doesn't work on 64 bit arch

[Keir Fraser]

On 17 Nov 2005, at 22:40, Rob Gardner wrote:

> The xentrace_format script doesn't work on x86/64. Python pads the 
> input structure because the first field is 32 bits and the next is 64 
> bits, whereas x86-32 doesn't pad. The quick fix is to read the cpu id 
> separately as a 32bit value, then read the rest of the trace record. 
> Here is a little patch that does that. Tested on x86/32 SMP and 
> x86/64.

Your mail client has garbled the patch. Please re-send as an attachment.

  -- Keir