George Dunlap
2011-Jun-30 10:45 UTC
[Xen-devel] [PATCH] xen tracing: Allow tracing to be enabled at boot
Add a "tevt_mask" parameter to the xen command-line, allowing
trace records to be gathered early in boot. They will be placed
into the trace buffers, and read when the user runs "xentrace".
Signed-off-by: George Dunlap <george.dunlap@eu.citrix.com>
diff -r 33717472f37e -r 48d08dc25c71 xen/common/trace.c
--- a/xen/common/trace.c Tue Jun 28 18:15:44 2011 +0100
+++ b/xen/common/trace.c Thu Jun 30 11:37:20 2011 +0100
@@ -45,7 +45,9 @@ CHECK_t_buf;
/* opt_tbuf_size: trace buffer size (in pages) for each cpu */
static unsigned int opt_tbuf_size;
+static unsigned int opt_tevt_mask;
integer_param("tbuf_size", opt_tbuf_size);
+integer_param("tevt_mask", opt_tevt_mask);
/* Pointers to the meta-data objects for all system trace buffers */
static struct t_info *t_info;
@@ -338,11 +340,21 @@ void __init init_trace_bufs(void)
{
register_cpu_notifier(&cpu_nfb);
- if ( opt_tbuf_size && alloc_trace_bufs(opt_tbuf_size) )
+ if ( opt_tbuf_size )
{
- printk(XENLOG_INFO "xentrace: allocation size %d failed,
disabling\n",
- opt_tbuf_size);
- opt_tbuf_size = 0;
+ if ( alloc_trace_bufs(opt_tbuf_size) )
+ {
+ printk("xentrace: allocation size %d failed,
disabling\n",
+ opt_tbuf_size);
+ opt_tbuf_size = 0;
+ }
+ else if ( opt_tevt_mask )
+ {
+ printk("xentrace: Starting tracing, enabling mask %x\n",
+ opt_tevt_mask);
+ tb_event_mask = opt_tevt_mask;
+ tb_init_done=1;
+ }
}
}
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