[Xen-devel] [PATCH v2] console: avoid printing no or null time stamps

["Jan Beulich" <JBeulich@xxxxxxxx>]

During early boot timestamps aren't very useful, as they're all zero
(in "boot" mode) or absent altogether (in "date" and "datems" modes).
Log "boot" format timestamps when the date formats aren't available yet,
and log raw timestamps when boot ones are still all zero. Also add a
"raw" mode.

For the ARM side get_cycles() to produce a meaningful value, ARM's
cycle_t gets changed to uint64_t.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v2: Mention ARM cycle_t change in description. Keep sprintf()-s
    separate.
---
ARM side build-tested only.

--- a/docs/misc/xen-command-line.markdown
+++ b/docs/misc/xen-command-line.markdown
@@ -413,7 +413,7 @@ only available when used together with `
 makes sense on its own.
 
 ### console\_timestamps
-> `= none | date | datems | boot`
+> `= none | date | datems | boot | raw`
 
 > Default: `none`
 
@@ -428,6 +428,8 @@ Specify which timestamp format Xen shoul
     * `[YYYY-MM-DD HH:MM:SS.mmm]`
 * `boot`: Seconds and microseconds since boot
     * `[SSSSSS.uuuuuu]`
++ `raw`: Raw platform ticks, architecture and implementation dependent
+    * `[XXXXXXXXXXXXXXXX]`
 
 For compatibility with the older boolean parameter, specifying
 `console_timestamps` alone will enable the `date` option.
--- a/xen/drivers/char/console.c
+++ b/xen/drivers/char/console.c
@@ -68,7 +68,8 @@ enum con_timestamp_mode
     TSM_NONE,          /* No timestamps */
     TSM_DATE,          /* [YYYY-MM-DD HH:MM:SS] */
     TSM_DATE_MS,       /* [YYYY-MM-DD HH:MM:SS.mmm] */
-    TSM_BOOT           /* [SSSSSS.uuuuuu] */
+    TSM_BOOT,          /* [SSSSSS.uuuuuu] */
+    TSM_RAW,           /* [XXXXXXXXXXXXXXXX] */
 };
 
 static enum con_timestamp_mode __read_mostly opt_con_timestamp_mode = TSM_NONE;
@@ -676,6 +677,8 @@ static int parse_console_timestamps(cons
         opt_con_timestamp_mode = TSM_DATE_MS;
     else if ( !strcmp(s, "boot") )
         opt_con_timestamp_mode = TSM_BOOT;
+    else if ( !strcmp(s, "raw") )
+        opt_con_timestamp_mode = TSM_RAW;
     else if ( !strcmp(s, "none") )
         opt_con_timestamp_mode = TSM_NONE;
     else
@@ -699,25 +702,36 @@ static void printk_start_of_line(const c
         tm = wallclock_time(&nsec);
 
         if ( tm.tm_mday == 0 )
-            return;
-
-        if ( opt_con_timestamp_mode == TSM_DATE )
+            /* nothing */;
+        else if ( opt_con_timestamp_mode == TSM_DATE )
+        {
             snprintf(tstr, sizeof(tstr), "[%04u-%02u-%02u %02u:%02u:%02u] ",
                      1900 + tm.tm_year, tm.tm_mon + 1, tm.tm_mday,
                      tm.tm_hour, tm.tm_min, tm.tm_sec);
+            break;
+        }
         else
+        {
             snprintf(tstr, sizeof(tstr),
                      "[%04u-%02u-%02u %02u:%02u:%02u.%03"PRIu64"] ",
                      1900 + tm.tm_year, tm.tm_mon + 1, tm.tm_mday,
                      tm.tm_hour, tm.tm_min, tm.tm_sec, nsec / 1000000);
-        break;
-
+            break;
+        }
+        /* fall through */
     case TSM_BOOT:
         sec = NOW();
         nsec = do_div(sec, 1000000000);
 
-        snprintf(tstr, sizeof(tstr), "[%5"PRIu64".%06"PRIu64"] ",
-                 sec, nsec / 1000);
+        if ( sec | nsec )
+        {
+            snprintf(tstr, sizeof(tstr), "[%5"PRIu64".%06"PRIu64"] ",
+                     sec, nsec / 1000);
+            break;
+        }
+        /* fall through */
+    case TSM_RAW:
+        snprintf(tstr, sizeof(tstr), "[%016"PRIx64"] ", get_cycles());
         break;
 
     case TSM_NONE:
--- a/xen/include/asm-arm/time.h
+++ b/xen/include/asm-arm/time.h
@@ -5,11 +5,11 @@
     DT_MATCH_COMPATIBLE("arm,armv7-timer"), \
     DT_MATCH_COMPATIBLE("arm,armv8-timer")
 
-typedef unsigned long cycles_t;
+typedef uint64_t cycles_t;
 
 static inline cycles_t get_cycles (void)
 {
-        return 0;
+        return READ_SYSREG64(CNTPCT_EL0);
 }
 
 /* List of timer's IRQ */
--- a/xen/include/asm-x86/time.h
+++ b/xen/include/asm-x86/time.h
@@ -28,7 +28,7 @@ extern bool disable_tsc_sync;
 
 static inline cycles_t get_cycles(void)
 {
-    return rdtsc();
+    return rdtsc_ordered();
 }
 
 unsigned long




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