Document system start options...

... and warn if bad values are specified.

Signed-off-by: Paul Durrant <pdurrant@amazon.com>

diff --git a/README.md b/README.md
index 7bb3a8344941cf3937b6a27abd398c4af1e90aea..547628e76c86c5828e6560af756e86d603d47873 100644 (file)
--- a/README.md
+++ b/README.md
@@ -42,3 +42,35 @@ get_xen_headers.py
 
 This will import any necessary headers from a given tag of that Xen
 repository at git://xenbits.xen.org/xen.git.
+
+System Start Options
+====================
+
+Behaviour in both the xen.sys and xenbus.sys can be configured by 'system
+start options'. These options can be supplied on the Windows loader 'command
+line', which can be set by hitting F10 during early boot or appended to by
+setting the value of 'loadptions' using bcdedit.
+
+XEN:DBG_PRINT=ON|OFF (default: ON)
+
+This option determines with DbgPrint() output is intercepted and logged.
+(To reduce noise, messages not prefixed with 'XEN' are ignored).
+
+XEN:BOOT_EMULATED=TRUE|FALSE (default: FALSE)
+
+This option avoids unplugging the first emulated IDE device, which is
+useful when debugging the XENVBD driver (since the system disk remains
+emulated).
+
+XEN:BALLOON=ON|OFF (default: ON)
+
+This option controls whether the XENBUS_BALLOON interface and thread is
+enabled.
+
+XEN:WATCHDOG=<TIME-OUT> (default: 0 minimum: 10)
+
+This options determine whether the domain watchdog is enabled. If a non-zero
+time-out (in seconds) is specified then the watchdog will be enabled. The
+watchdog is patted by VIRQ_TIMER handlers and hence this is useful to
+detect length stalls in event delivery or handling. The minimum time-out
+value is 10s.

diff --git a/src/xen/log.c b/src/xen/log.c
index ed7e484cddc74fec9b8e137bbbb2ca4f2b955482..5044070392f21b47f7baecf195b74f035c0acf63 100644 (file)
--- a/src/xen/log.c
+++ b/src/xen/log.c
@@ -695,6 +695,8 @@ __LogDbgPrintCallbackEnable(
 
     if (strcmp(Value, "OFF") == 0)
         Enable = FALSE;
+    else if (strcmp(Value, "ON") != 0)
+        Warning("UNRECOGNIZED VALUE OF %s: %s\n", Key, Value);
 
     RegistryFreeSzValue(Option);
 

diff --git a/src/xen/unplug.c b/src/xen/unplug.c
index cf17b69b2442e88f1f7212e83b1df9b84cc9955c..c9a29a6a3c8925d4764be1f31760e820c8312b5c 100644 (file)
--- a/src/xen/unplug.c
+++ b/src/xen/unplug.c
@@ -93,6 +93,8 @@ UnplugSetBootEmulated(
 
     if (strcmp(Value, "TRUE") == 0)
         Context->BootEmulated = TRUE;
+    else if (strcmp(Value, "FALSE") != 0)
+        Warning("UNRECOGNIZED VALUE OF %s: %s\n", Key, Value);
 
     RegistryFreeSzValue(Option);
 }

diff --git a/src/xenbus/fdo.c b/src/xenbus/fdo.c
index d164aab8a6044e9b60c56882a67b27f69f598797..5419be4911cee0f83627b7d6592618f053d0cb3d 100644 (file)
--- a/src/xenbus/fdo.c
+++ b/src/xenbus/fdo.c
@@ -5579,6 +5579,8 @@ FdoBalloonInitialize(
 
     if (strcmp(Value, "OFF") == 0)
         Enabled = FALSE;
+    else if (strcmp(Value, "ON") != 0)
+        Warning("UNRECOGNIZED VALUE OF %s: %s\n", Key, Value);
 
     RegistryFreeSzValue(Option);