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Subject[PATCH 09/10] xen: add some debug output for failed multicalls
Multicalls are expected to never fail, and the normal response to a
failed multicall is very terse. In the interests of better
debuggability, add some more verbose output. It may be worth turning
this off once it all seems more tested.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>

---
arch/i386/xen/multicalls.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)

===================================================================
--- a/arch/i386/xen/multicalls.c
+++ b/arch/i386/xen/multicalls.c
@@ -26,11 +26,16 @@

#include "multicalls.h"

+#define MC_DEBUG 1
+
#define MC_BATCH 32
#define MC_ARGS (MC_BATCH * 16 / sizeof(u64))

struct mc_buffer {
struct multicall_entry entries[MC_BATCH];
+#if MC_DEBUG
+ struct multicall_entry debug[MC_BATCH];
+#endif
u64 args[MC_ARGS];
struct callback {
void (*fn)(void *);
@@ -56,11 +61,31 @@ void xen_mc_flush(void)
local_irq_save(flags);

if (b->mcidx) {
+#if MC_DEBUG
+ memcpy(b->debug, b->entries,
+ b->mcidx * sizeof(struct multicall_entry));
+#endif
+
if (HYPERVISOR_multicall(b->entries, b->mcidx) != 0)
BUG();
for (i = 0; i < b->mcidx; i++)
if (b->entries[i].result < 0)
ret++;
+
+#if MC_DEBUG
+ if (ret) {
+ printk(KERN_ERR "%d multicall(s) failed: cpu %d\n",
+ ret, smp_processor_id());
+ for(i = 0; i < b->mcidx; i++) {
+ printk(" call %2d/%d: op=%lu arg=[%lx] result=%ld\n",
+ i+1, b->mcidx,
+ b->debug[i].op,
+ b->debug[i].args[0],
+ b->entries[i].result);
+ }
+ }
+#endif
+
b->mcidx = 0;
b->argidx = 0;
} else
--

-
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