[PATCH] xen/console: add keyhandler to print Xen version

[dmkhn@xxxxxxxxx]

Add Xen version printout via keyhandler mechanism.

That is useful for debugging systems that have been left intact for a long
time.

Signed-off-by: Denis Mukhin <dmukhin@xxxxxxxx>
---
 xen/common/version.c       |  2 --
 xen/drivers/char/console.c | 31 ++++++++++++++++++++++++++-----
 2 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/xen/common/version.c b/xen/common/version.c
index bc3714b45f..9e47ff0744 100644
--- a/xen/common/version.c
+++ b/xen/common/version.c
@@ -210,8 +210,6 @@ void __init xen_build_init(void)
         }
     }
 #endif /* CONFIG_X86 */
-    if ( !rc )
-        printk(XENLOG_INFO "build-id: %*phN\n", build_id_len, build_id_p);
 }
 #endif /* BUILD_ID */
 /*
diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
index 73d24a7821..4f945f3bca 100644
--- a/xen/drivers/char/console.c
+++ b/xen/drivers/char/console.c
@@ -974,6 +974,28 @@ void guest_printk(const struct domain *d, const char *fmt, 
...)
     va_end(args);
 }
 
+static void xen_print_version(void)
+{
+    const char *str = NULL;
+    unsigned int str_len;
+
+    printk("Xen version %d.%d%s (%s@%s) (%s) %s %s\n",
+           xen_major_version(), xen_minor_version(), xen_extra_version(),
+           xen_compile_by(), xen_compile_domain(), xen_compiler(),
+           xen_build_info(), xen_compile_date());
+
+    printk("Latest ChangeSet: %s\n", xen_changeset());
+
+    if ( !xen_build_id((const void **)&str, &str_len) )
+        printk(XENLOG_INFO "build-id: %*phN\n", str_len, str);
+}
+
+static void cf_check do_print_version(unsigned char key, bool unused)
+{
+    printk("'%c' pressed -> printing Xen version\n", key);
+    xen_print_version();
+}
+
 void __init console_init_preirq(void)
 {
     char *p;
@@ -1024,15 +1046,12 @@ void __init console_init_preirq(void)
     nrspin_lock(&console_lock);
     __putstr(xen_banner());
     nrspin_unlock(&console_lock);
-    printk("Xen version %d.%d%s (%s@%s) (%s) %s %s\n",
-           xen_major_version(), xen_minor_version(), xen_extra_version(),
-           xen_compile_by(), xen_compile_domain(), xen_compiler(),
-           xen_build_info(), xen_compile_date());
-    printk("Latest ChangeSet: %s\n", xen_changeset());
 
     /* Locate and print the buildid, if applicable. */
     xen_build_init();
 
+    xen_print_version();
+
     if ( opt_sync_console )
     {
         serial_start_sync(sercon_handle);
@@ -1120,6 +1139,8 @@ void __init console_endboot(void)
                             "decrease log level threshold", 0);
     register_irq_keyhandler('G', &do_toggle_guest,
                             "toggle host/guest log level adjustment", 0);
+    register_irq_keyhandler('~', &do_print_version,
+                            "print Xen version", 0);
 
     /* Serial input is directed to DOM0 by default. */
     switch_serial_input();
-- 
2.34.1