Log to files in /var/log/xen and add compile-time loglevel.

17 files changed, 186 insertions, 112 deletions

diff --git a/src/comm.c b/src/comm.c
index 09a9b38..0cc078f 100644
--- a/src/comm.c
+++ b/src/comm.c
@@ -3,6 +3,7 @@
 #include <stdio.h>
 #include <string.h>
 
+#include "fd.h"
 #include "comm.h"
 #include "view.h"
 #include "buffer.h"
@@ -69,11 +70,11 @@ comm_create(struct client *c, struct buffer *b, struct lin_message *m)
 {
     struct view *v = view_lookup(c, m->view);
     if (v)
-	fprintf(stderr, "Warning: view %x already exists.\n", m->view);
+	FD_LOG(1, "Warning: view %x already exists.\n", m->view);
     else {
 	v = view_new(c, b, m->view, 0);
 	if (!v) {
-	    fprintf(stderr, "Failed to create view!\n");
+	    FD_LOG(0, "Failed to create view!\n");
 	    return;
 	}
 	v->mapped = 0;
@@ -87,7 +88,7 @@ comm_update(struct client *c, struct buffer *b, struct lin_message *m)
 {
     struct view *v = view_lookup(c, m->view);
     if (!v) {
-	fprintf(stderr, "Warning: view %x does not exist.\n", m->view);
+	FD_LOG(1, "Warning: view %x does not exist.\n", m->view);
 	return;
     }
 
diff --git a/src/common.h b/src/common.h
index 95bb849..1677148 100644
--- a/src/common.h
+++ b/src/common.h
@@ -5,6 +5,10 @@
 #define LINPICKER_TOKEN "@i"
 #define LINPICKER_VPORT 6000
 
+/* Log files */
+#define SERVER_LOG "/var/log/xen/linpicker-server.log"
+#define MONITOR_LOG "/var/log/xen/linpicker-monitor.log"
+
 /* Security label dimensions */
 #define FONT_FILE PKGDATADIR "/decker.ttf"
 #define SERVER_BG_FILE PKGDATADIR "/serverbg.rgb"
diff --git a/src/display.h b/src/display.h
index 6cc5be5..1248ad2 100644
--- a/src/display.h
+++ b/src/display.h
@@ -20,6 +20,7 @@
 #include <directfb.h>
 
 #include "common.h"
+#include "fd.h"
 #include "view.h"
 #include "buffer.h"
 #include "client.h"
@@ -113,13 +114,13 @@ display_get_width(void);
 int
 display_get_height(void);
 
-#define DFBCHECK(x...) \
-        {                                                                      \
-           int ret = x;                                                        \
-           if (ret != DFB_OK) {                                                \
-              fprintf( stderr, "%s <%d>:\n\t", __FILE__, __LINE__ );           \
-              DirectFBErrorFatal( #x, ret );                                   \
-           }                                                                   \
-        }
+#define DFBCHECK(x...)							\
+    {									\
+	int ret = x;							\
+	if (ret != DFB_OK) {						\
+	    FD_LOG(0, "%s <%d>:\n\t", __FILE__, __LINE__ );		\
+	    DirectFBErrorFatal( #x, ret );				\
+	}								\
+    }
 
 #endif /* _LINPICKER_DISPLAY_H_ */
diff --git a/src/fd.c b/src/fd.c
index 234c867..516eedc 100644
--- a/src/fd.c
+++ b/src/fd.c
@@ -1,14 +1,70 @@
+#define _GNU_SOURCE
 #include <sys/types.h>
 #include <sys/select.h>
 #include <stdlib.h>
 #include <stdio.h>
+#include <stdarg.h>
 #include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
 #include <errno.h>
 
 #include "common.h"
 #include "sys-queue.h"
 #include "fd.h"
 
+void
+fd_vlog(const char *fmt, va_list args)
+{
+    vfprintf(stderr, fmt, args);
+}
+
+void
+fd_log(const char *fmt, ...)
+{
+    va_list args;
+    va_start(args, fmt);
+    vfprintf(stderr, fmt, args);
+    va_end(args);
+}
+
+int
+fd_open_logfile(const char *path)
+{
+    int nullfd, logfd;
+    char *oldpath;
+
+    /* Redirect stdin and stdout to /dev/null */
+    nullfd = open("/dev/null", O_RDWR);
+    if (nullfd < 0) {
+	perror("Failed to open /dev/null");
+	return -1;
+    }
+    dup2(nullfd, 0);
+    dup2(nullfd, 1);
+
+    /* Attempt to save the old logfile */
+    if (asprintf(&oldpath, "%s.1", path) > 0) {
+	rename(path, oldpath);
+	free(oldpath);
+    }
+
+    /* Attempt to redirect stderr to the logfile */
+    logfd = open(path, O_WRONLY|O_CREAT|O_TRUNC);
+    if (logfd < 0) {
+	fprintf(stderr, "Warning: failed to open logfile '%s': %m\n", path);
+	dup2(nullfd, 2);
+    } else {
+	dup2(logfd, 2);
+	close(logfd);
+    }
+
+    close(nullfd);
+    return 0;
+}
+
+/* -------------------------------------------------------------------- */
+
 struct listener {
     LIST_ENTRY(listener) next;
     int fd;
@@ -63,7 +119,7 @@ fd_run_select(void)
     if (rc < 0) {
 	if (errno == EAGAIN || errno == EINTR)
 	    return 0;
-	perror("select");
+	FD_LOG(0, "select() failed: %m\n");
 	return -1;
     }
 
@@ -84,7 +140,7 @@ loop:
 }
 
 void
-fd_free_handlers(void)
+fd_shutdown(void)
 {
     struct listener *l;
 
diff --git a/src/fd.h b/src/fd.h
index 64da71d..57ccc1b 100644
--- a/src/fd.h
+++ b/src/fd.h
@@ -1,8 +1,25 @@
 #ifndef _LINPICKER_FD_H_
 #define _LINPICKER_FD_H_
 
+#include "config.h"
+
 typedef void (*fd_handler)(void *closure);
 
+#define FD_LOG(lvl, msg...)			\
+    do {					\
+	if (lvl <= LOGLEVEL)			\
+	    fd_log(msg);			\
+    } while (0)
+
+void
+fd_vlog(const char *fmt, va_list args);
+
+void
+fd_log(const char *fmt, ...);
+
+int
+fd_open_logfile(const char *path);
+
 int
 fd_set_handler(int fd, fd_handler callback, void *closure);
 
@@ -10,6 +27,6 @@ int
 fd_run_select(void);
 
 void
-fd_free_handlers(void);
+fd_shutdown(void);
 
 #endif /* _LINPICKER_FD_H_ */
diff --git a/src/input.c b/src/input.c
index 7d7a3b8..cb45d79 100644
--- a/src/input.c
+++ b/src/input.c
@@ -194,7 +194,7 @@ configure_absolute_device(int fd)
     ai.maximum = display_get_width() - 1;
 
     if (ioctl(fd, EVIOCSABS(ABS_X), &ai) < 0) {
-	perror("EVIOCSABS");
+	FD_LOG(0, "ioctl EVIOCSABS failed: %m\n");
 	return -1;
     }
 
@@ -205,7 +205,7 @@ configure_absolute_device(int fd)
     ai.maximum = display_get_height() - 1;
 
     if (ioctl(fd, EVIOCSABS(ABS_Y), &ai) < 0) {
-	perror("EVIOCSABS");
+	FD_LOG(0, "ioctl EVIOCSABS failed: %m\n");
 	return -1;
     }
 
@@ -252,7 +252,7 @@ open_device(const char *path)
     TAILQ_INSERT_TAIL(&devices, d, next);
     return 0;
 err:
-    fprintf(stderr, "Warning: failed to open device '%s' on %s\n", name, path);
+    FD_LOG(1, "Warning: failed to open device '%s' on %s\n", name, path);
     free(d);
     if (fd >= 0) {
 	ioctl(fd, EVIOCGRAB, 0);
@@ -331,7 +331,7 @@ device_removed(struct udev_device *udev_device)
 	    return;
 	}
 
-    fprintf(stderr, "Warning: failed to close device %s\n", path);
+    FD_LOG(2, "Warning: failed to close device %s\n", path);
 }
 
 static void
@@ -389,7 +389,7 @@ input_initialize(int argc, char *argv[])
 
     return 0;
 err:
-    fprintf(stderr, "Failed to set up udev.\n");
+    FD_LOG(0, "Failed to set up udev.\n");
     return -1;
 }
 
diff --git a/src/local.c b/src/local.c
index a32b955..f22eaa0 100644
--- a/src/local.c
+++ b/src/local.c
@@ -27,7 +27,7 @@ local_process(void *closure)
 	if (rc < 0) {
 		if (errno == EAGAIN || errno == EINTR)
 			return;
-		perror("recv");
+		FD_LOG(0, "recv() failed: %m\n");
 		return;
 	} else if (rc == 1) {
 		switch (msg) {
@@ -49,7 +49,7 @@ local_init(int argc, char **argv)
 	/* Listen on a local socket */
 	sd = socket(AF_UNIX, SOCK_DGRAM, 0);
 	if (sd < 0) {
-		perror("socket");
+		FD_LOG(0, "socket() failed: %m\n");
 		return -1;
 	}
 
@@ -59,7 +59,7 @@ local_init(int argc, char **argv)
 
 	rc = bind(sd, (struct sockaddr *)&addr, sizeof(addr));
 	if (rc < 0) {
-		perror("bind");
+		FD_LOG(0, "bind() failed: %m\n");
 		return -1;
 	}
 
diff --git a/src/monitor.c b/src/monitor.c
index 17253ac..c129b63 100644
--- a/src/monitor.c
+++ b/src/monitor.c
@@ -7,9 +7,10 @@
 #include <signal.h>
 #include <errno.h>
 
+#include "common.h"
+#include "fd.h"
 #include "xen_backend.h"
 #include "sys-queue.h"
-#include "fd.h"
 
 extern int xenfb_monitor_init(void);
 
@@ -35,6 +36,10 @@ int main (int argc, char *argv[])
     sigaction(SIGINT, &sa, NULL);
     sigaction(SIGTERM, &sa, NULL);
 
+    /* Open logfile */
+    if (fd_open_logfile(MONITOR_LOG) < 0)
+	return 1;
+
     /* Initialize subsystems */
     if (xen_be_init() < 0)
 	return 1;
@@ -45,6 +50,6 @@ int main (int argc, char *argv[])
     while (!timetodie && fd_run_select() == 0);
 
     /* Shut down */
-    fd_free_handlers();
+    fd_shutdown();
     return 0;
 }
diff --git a/src/server.c b/src/server.c
index 1ba43be..033bbe4 100644
--- a/src/server.c
+++ b/src/server.c
@@ -17,12 +17,13 @@
 #include <signal.h>
 #include <errno.h>
 
+#include "common.h"
+#include "fd.h"
 #include "xen_backend.h"
 #include "sys-queue.h"
 #include "display.h"
 #include "input.h"
 #include "local.h"
-#include "fd.h"
 
 static int timetodie;
 
@@ -46,6 +47,10 @@ int main (int argc, char *argv[])
     sigaction(SIGINT, &sa, NULL);
     sigaction(SIGTERM, &sa, NULL);
 
+    /* Open logfile */
+    if (fd_open_logfile(SERVER_LOG) < 0)
+	return 1;
+
     /* Initialize subsystems */
     if (local_init(argc, argv) < 0)
 	return 1;
@@ -62,6 +67,6 @@ int main (int argc, char *argv[])
     /* Shut down */
     input_shutdown();
     display_shutdown();
-    fd_free_handlers();
+    fd_shutdown();
     return 0;
 }
diff --git a/src/xen_backend.c b/src/xen_backend.c
index d6fca41..73f1a0b 100644
--- a/src/xen_backend.c
+++ b/src/xen_backend.c
@@ -44,7 +44,6 @@ const char *xen_protocol;
 
 /* private */
 static TAILQ_HEAD(XenDeviceHead, XenDevice) xendevs = TAILQ_HEAD_INITIALIZER(xendevs);
-static int debug = 0;
 
 /* ------------------------------------------------------------- */
 
@@ -140,7 +139,7 @@ int xen_be_set_state(struct XenDevice *xendev, enum xenbus_state state)
     rc = xen_linpicker_be_set_state(xendev, state);
     if (rc < 0)
 	return rc;
-    xen_be_printf(xendev, 1, "backend state: %s -> %s\n",
+    XEN_BE_LOG(xendev, 1, "backend state: %s -> %s\n",
 		  xenbus_strstate(xendev->be_state), xenbus_strstate(state));
     xendev->be_state = state;
     return 0;
@@ -201,19 +200,18 @@ static struct XenDevice *xen_be_get_xendev(const char *type, int dom, int dev,
 	     xendev->dom, xendev->type, xendev->dev);
     free(dom0);
 
-    xendev->debug      = debug;
     xendev->local_port = -1;
 
     xendev->evtchndev = xc_evtchn_open(NULL, 0);
     if (xendev->evtchndev < 0) {
-	xen_be_printf(NULL, 0, "can't open evtchn device\n");
+	XEN_BE_LOG(NULL, 0, "can't open evtchn device\n");
 	goto out_err1;
     }
     fcntl(xc_evtchn_fd(xendev->evtchndev), F_SETFD, FD_CLOEXEC);
 
     xendev->gnttabdev = xc_gnttab_open(NULL, 0);
     if (xendev->gnttabdev < 0) {
-	xen_be_printf(NULL, 0, "can't open gnttab device\n");
+	XEN_BE_LOG(NULL, 0, "can't open gnttab device\n");
 	goto out_err2;
     }
 
@@ -285,7 +283,7 @@ static void xen_be_backend_changed(struct XenDevice *xendev, const char *node)
     }
 
     if (node) {
-	xen_be_printf(xendev, 2, "backend update: %s\n", node);
+	XEN_BE_LOG(xendev, 2, "backend update: %s\n", node);
 	if (xendev->ops->backend_changed)
 	    xendev->ops->backend_changed(xendev, node);
     }
@@ -299,7 +297,7 @@ static void xen_be_frontend_changed(struct XenDevice *xendev, const char *node)
 	if (xenstore_read_fe_int(xendev, "state", &fe_state) == -1)
 	    fe_state = XenbusStateUnknown;
 	if (xendev->fe_state != fe_state)
-	    xen_be_printf(xendev, 1, "frontend state: %s -> %s\n",
+	    XEN_BE_LOG(xendev, 1, "frontend state: %s -> %s\n",
 			  xenbus_strstate(xendev->fe_state),
 			  xenbus_strstate(fe_state));
 	xendev->fe_state = fe_state;
@@ -308,11 +306,11 @@ static void xen_be_frontend_changed(struct XenDevice *xendev, const char *node)
 	free(xendev->protocol);
 	xendev->protocol = xenstore_read_fe_str(xendev, "protocol");
 	if (xendev->protocol)
-	    xen_be_printf(xendev, 1, "frontend protocol: %s\n", xendev->protocol);
+	    XEN_BE_LOG(xendev, 1, "frontend protocol: %s\n", xendev->protocol);
     }
 
     if (node) {
-	xen_be_printf(xendev, 2, "frontend update: %s\n", node);
+	XEN_BE_LOG(xendev, 2, "frontend update: %s\n", node);
 	if (xendev->ops->frontend_changed)
 	    xendev->ops->frontend_changed(xendev, node);
     }
@@ -335,14 +333,14 @@ static int xen_be_try_setup(struct XenDevice *xendev)
 
     xendev->fe = xenstore_read_be_str(xendev, "frontend");
     if (xendev->fe == NULL) {
-	xen_be_printf(xendev, 0, "reading frontend path failed\n");
+	XEN_BE_LOG(xendev, 0, "reading frontend path failed\n");
 	return -1;
     }
 
     /* setup frontend watch */
     snprintf(token, sizeof(token), "fe:%p", xendev);
     if (!xs_watch(xenstore, xendev->fe, token)) {
-	xen_be_printf(xendev, 0, "watching frontend path (%s) failed\n",
+	XEN_BE_LOG(xendev, 0, "watching frontend path (%s) failed\n",
 		      xendev->fe);
 	return -1;
     }
@@ -366,14 +364,14 @@ static int xen_be_try_init(struct XenDevice *xendev)
     int rc = 0;
 
     if (!xendev->online) {
-	xen_be_printf(xendev, 1, "not online\n");
+	XEN_BE_LOG(xendev, 1, "not online\n");
 	return -1;
     }
 
     if (xendev->ops->init)
 	rc = xendev->ops->init(xendev);
     if (rc != 0) {
-	xen_be_printf(xendev, 1, "init() failed\n");
+	XEN_BE_LOG(xendev, 1, "init() failed\n");
 	return rc;
     }
 
@@ -396,9 +394,9 @@ static int xen_be_try_initialise(struct XenDevice *xendev)
     if (xendev->fe_state != XenbusStateInitialised  &&
 	xendev->fe_state != XenbusStateConnected) {
 	if (xendev->ops->flags & DEVOPS_FLAG_IGNORE_STATE) {
-	    xen_be_printf(xendev, 2, "frontend not ready, ignoring\n");
+	    XEN_BE_LOG(xendev, 2, "frontend not ready, ignoring\n");
 	} else {
-	    xen_be_printf(xendev, 2, "frontend not ready (yet)\n");
+	    XEN_BE_LOG(xendev, 2, "frontend not ready (yet)\n");
 	    return -1;
 	}
     }
@@ -406,7 +404,7 @@ static int xen_be_try_initialise(struct XenDevice *xendev)
     if (xendev->ops->initialise)
 	rc = xendev->ops->initialise(xendev);
     if (rc != 0) {
-	xen_be_printf(xendev, 0, "initialise() failed\n");
+	XEN_BE_LOG(xendev, 0, "initialise() failed\n");
 	return rc;
     }
 
@@ -426,9 +424,9 @@ static void xen_be_try_connected(struct XenDevice *xendev)
 
     if (xendev->fe_state != XenbusStateConnected) {
        if (xendev->ops->flags & DEVOPS_FLAG_IGNORE_STATE) {
-           xen_be_printf(xendev, 2, "frontend not ready, ignoring\n");
+           XEN_BE_LOG(xendev, 2, "frontend not ready, ignoring\n");
        } else {
-           xen_be_printf(xendev, 2, "frontend not ready (yet)\n");
+           XEN_BE_LOG(xendev, 2, "frontend not ready (yet)\n");
            return;
        }
     }
@@ -459,7 +457,7 @@ static int xen_be_try_reset(struct XenDevice *xendev)
     if (xendev->fe_state != XenbusStateInitialising)
         return -1;
 
-    xen_be_printf(xendev, 1, "device reset (for re-connect)\n");
+    XEN_BE_LOG(xendev, 1, "device reset (for re-connect)\n");
     xen_be_set_state(xendev, XenbusStateInitialising);
     return 0;
 }
@@ -520,7 +518,7 @@ static int xenstore_scan(const char *type, int dom, struct XenDevOps *ops)
     snprintf(path, sizeof(path), "%s/backend/%s/%d", dom0, type, dom);
     free(dom0);
     if (!xs_watch(xenstore, path, token)) {
-	xen_be_printf(NULL, 0, "xen be: watching backend path (%s) failed\n", path);
+	XEN_BE_LOG(NULL, 0, "xen be: watching backend path (%s) failed\n", path);
 	return -1;
     }
 
@@ -616,7 +614,7 @@ static void xen_be_evtchn_event(void *opaque)
 
     port = xc_evtchn_pending(xendev->evtchndev);
     if (port != xendev->local_port) {
-	xen_be_printf(xendev, 0, "xc_evtchn_pending returned %d (expected %d)\n",
+	XEN_BE_LOG(xendev, 0, "xc_evtchn_pending returned %d (expected %d)\n",
 		      port, xendev->local_port);
 	return;
     }
@@ -637,7 +635,7 @@ int xen_be_init(void)
     if (!xenstore)
 	xenstore = xs_domain_open();
     if (!xenstore) {
-	xen_be_printf(NULL, 0, "can't connect to xenstored\n");
+	XEN_BE_LOG(NULL, 0, "can't connect to xenstored\n");
 	return -1;
     }
 
@@ -646,12 +644,12 @@ int xen_be_init(void)
 
     xen_xc = xc_interface_open(0,0,0);
     if (!xen_xc) {
-	xen_be_printf(NULL, 0, "can't open xen interface\n");
+	XEN_BE_LOG(NULL, 0, "can't open xen interface\n");
 	goto err;
     }
 
     if (xen_linpicker_init(xenstore, xen_xc) != 0) {
-	xen_be_printf(NULL, 0, "intro/release watch setup failed\n");
+	XEN_BE_LOG(NULL, 0, "intro/release watch setup failed\n");
 	goto err2;
     }
 
@@ -679,10 +677,10 @@ int xen_be_bind_evtchn(struct XenDevice *xendev)
     xendev->local_port = xc_evtchn_bind_interdomain
 	(xendev->evtchndev, xendev->dom, xendev->remote_port);
     if (xendev->local_port == -1) {
-	xen_be_printf(xendev, 0, "xc_evtchn_bind_interdomain failed\n");
+	XEN_BE_LOG(xendev, 0, "xc_evtchn_bind_interdomain failed\n");
 	return -1;
     }
-    xen_be_printf(xendev, 2, "bind evtchn port %d\n", xendev->local_port);
+    XEN_BE_LOG(xendev, 2, "bind evtchn port %d\n", xendev->local_port);
     fd_set_handler(xc_evtchn_fd(xendev->evtchndev),
 			xen_be_evtchn_event, xendev);
     return 0;
@@ -694,7 +692,7 @@ void xen_be_unbind_evtchn(struct XenDevice *xendev)
 	return;
     fd_set_handler(xc_evtchn_fd(xendev->evtchndev), NULL, NULL);
     xc_evtchn_unbind(xendev->evtchndev, xendev->local_port);
-    xen_be_printf(xendev, 2, "unbind evtchn port %d\n", xendev->local_port);
+    XEN_BE_LOG(xendev, 2, "unbind evtchn port %d\n", xendev->local_port);
     xendev->local_port = -1;
 }
 
@@ -703,37 +701,16 @@ int xen_be_send_notify(struct XenDevice *xendev)
     return xc_evtchn_notify(xendev->evtchndev, xendev->local_port);
 }
 
-/*
- * msg_level:
- *  0 == errors (stderr + logfile).
- *  1 == informative debug messages (logfile only).
- *  2 == noisy debug messages (logfile only).
- *  3 == will flood your log (logfile only).
- */
-void xen_be_printf(struct XenDevice *xendev, int msg_level, const char *fmt, ...)
+void xen_be_printf(struct XenDevice *xendev, const char *fmt, ...)
 {
     va_list args;
 
-    if (xendev) {
-//        if (msg_level > xendev->debug)
-//            return;
-//        qemu_log("xen be: %s: ", xendev->name);
-        if (msg_level <= 2)
-            fprintf(stderr, "xen be: %s: ", xendev->name);
-    } else {
-//        if (msg_level > debug)
-//            return;
-//        qemu_log("xen be core: ");
-        if (msg_level <= 2)
-            fprintf(stderr, "xen be core: ");
-    }
-//    va_start(args, fmt);
-//    qemu_log_vprintf(fmt, args);
-//    va_end(args);
-    if (msg_level <= 2) {
-        va_start(args, fmt);
-        vfprintf(stderr, fmt, args);
-        va_end(args);
-    }
-//    qemu_log_flush();
+    if (xendev)
+	fd_log("xen be: %s: ", xendev->name);
+    else
+	fd_log("xen be core: ");
+
+    va_start(args, fmt);
+    fd_vlog(fmt, args);
+    va_end(args);
 }
diff --git a/src/xen_backend.h b/src/xen_backend.h
index 91255a2..8a36c75 100644
--- a/src/xen_backend.h
+++ b/src/xen_backend.h
@@ -89,8 +89,8 @@ int xen_be_set_state(struct XenDevice *xendev, enum xenbus_state state);
 int xen_be_bind_evtchn(struct XenDevice *xendev);
 void xen_be_unbind_evtchn(struct XenDevice *xendev);
 int xen_be_send_notify(struct XenDevice *xendev);
-void xen_be_printf(struct XenDevice *xendev, int msg_level, const char *fmt, ...)
-    __attribute__ ((format(printf, 3, 4)));
+void xen_be_printf(struct XenDevice *xendev, const char *fmt, ...)
+    __attribute__ ((format(printf, 2, 3)));
 
 /* actual backend drivers */
 extern struct XenDevOps xen_console_ops;      /* xen_console.c     */
diff --git a/src/xen_console.c b/src/xen_console.c
index 045b388..8f486a4 100644
--- a/src/xen_console.c
+++ b/src/xen_console.c
@@ -166,13 +166,13 @@ static void xencons_send(struct XenConsole *con)
     if (len < 1) {
 	if (!con->backlog) {
 	    con->backlog = 1;
-	    xen_be_printf(&con->xendev, 1, "backlog piling up, nobody listening?\n");
+	    XEN_BE_LOG(&con->xendev, 1, "backlog piling up, nobody listening?\n");
 	}
     } else {
 	buffer_advance(&con->buffer, len);
 	if (con->backlog && len == size) {
 	    con->backlog = 0;
-	    xen_be_printf(&con->xendev, 1, "backlog is gone\n");
+	    XEN_BE_LOG(&con->xendev, 1, "backlog is gone\n");
 	}
     }
 }
@@ -194,7 +194,7 @@ static int con_init(struct XenDevice *xendev)
 
     type = xenstore_read_str(con->console, "type");
     if (!type || 0 != strcmp(type, "ioemu")) {
-	xen_be_printf(xendev, 1, "not for me (type=%s)\n", type);
+	XEN_BE_LOG(xendev, 1, "not for me (type=%s)\n", type);
 	if (type)
 	    qemu_free(type);
 	return -1;
@@ -202,7 +202,7 @@ static int con_init(struct XenDevice *xendev)
     qemu_free(type);
 
     if (!serial_hds[con->xendev.dev])
-	xen_be_printf(xendev, 1, "WARNING: serial line %d not configured\n",
+	XEN_BE_LOG(xendev, 1, "WARNING: serial line %d not configured\n",
                       con->xendev.dev);
     else
         con->chr = serial_hds[con->xendev.dev];
@@ -239,7 +239,7 @@ static int con_initialise(struct XenDevice *xendev)
         qemu_chr_add_handlers(con->chr, xencons_can_receive, xencons_receive,
                               NULL, con);
 
-    xen_be_printf(xendev, 1, "ring mfn %d, remote port %d, local port %d, limit %zd\n",
+    XEN_BE_LOG(xendev, 1, "ring mfn %d, remote port %d, local port %d, limit %zd\n",
 		  con->ring_ref,
 		  con->xendev.remote_port,
 		  con->xendev.local_port,
diff --git a/src/xen_linpicker.h b/src/xen_linpicker.h
index a5e1d18..ce56883 100644
--- a/src/xen_linpicker.h
+++ b/src/xen_linpicker.h
@@ -5,6 +5,7 @@
 #include <xs.h>
 #include <xen/io/xenbus.h>
 
+#include "config.h"
 #include "common.h"
 #include "xen_backend.h"
 #include "fd.h"
@@ -12,6 +13,13 @@
 #include "display.h"
 #include "input.h"
 
+/* logging */
+#define XEN_BE_LOG(xendev, lvl, msg...)		\
+    do {					\
+	if (lvl <= LOGLEVEL)			\
+	    xen_be_printf(xendev, msg);		\
+    } while (0)
+
 /* domain creation watch */
 int xen_linpicker_init(struct xs_handle *, xc_interface*);
 int xen_linpicker_update(struct xs_handle *, xc_interface*, const char *);
diff --git a/src/xen_monitor.c b/src/xen_monitor.c
index 60f60e3..a2ce7d3 100644
--- a/src/xen_monitor.c
+++ b/src/xen_monitor.c
@@ -92,7 +92,7 @@ xen_linpicker_scan_domains(struct xs_handle *xenstore, int newdom)
 
     e = xs_directory(xenstore, XBT_NULL, "/local/domain", &n);
     if (!e) {
-	xen_be_printf(NULL, 0, "cannot list domains\n");
+	XEN_BE_LOG(NULL, 0, "cannot list domains\n");
 	return;
     }
 
diff --git a/src/xen_server.c b/src/xen_server.c
index 2cff419..8025c04 100644
--- a/src/xen_server.c
+++ b/src/xen_server.c
@@ -45,7 +45,7 @@ vchan_shutdown(struct dominfo *d)
     TAILQ_REMOVE(&vchans, d, next);
     fd_set_handler(d->fd, NULL, NULL);
     libvchan_close(d->ctrl);
-    fprintf(stderr, "Tore down vchan for domain %d\n", d->domid);
+    XEN_BE_LOG(NULL, 1, "Tore down vchan for domain %d\n", d->domid);
     free(d);
 }
 
@@ -128,7 +128,7 @@ vchan_setup(struct xs_handle *xenstore, xc_interface* xen_xc, const char *path)
     vchan_queue(d);
 
     TAILQ_INSERT_TAIL(&vchans, d, next);
-    fprintf(stderr, "Set up vchan for domain %d\n", domid);
+    XEN_BE_LOG(NULL, 1, "Set up vchan for domain %d\n", domid);
     return 0;
 err:
     free(d);
@@ -235,7 +235,7 @@ xen_linpicker_scan_domains(struct xs_handle *xenstore, int newdom)
 
     e = xs_directory(xenstore, XBT_NULL, "/local/domain", &n);
     if (!e) {
-	xen_be_printf(NULL, 0, "cannot list domains\n");
+	XEN_BE_LOG(NULL, 0, "cannot list domains\n");
 	return;
     }
 
diff --git a/src/xenfb_monitor.c b/src/xenfb_monitor.c
index c1a33fa..3a163f1 100644
--- a/src/xenfb_monitor.c
+++ b/src/xenfb_monitor.c
@@ -100,7 +100,7 @@ static int fb_initialise(struct XenDevice *xendev)
     if (update)
 	xenstore_write_be_int(xendev, "request-update", 1);
 
-    xen_be_printf(xendev, 1, "feature-update=%d, videoram=%d\n",
+    XEN_BE_LOG(xendev, 1, "feature-update=%d, videoram=%d\n",
 		  update, videoram);
     return 0;
 }
@@ -117,7 +117,7 @@ static void fb_frontend_changed(struct XenDevice *xendev, const char *node)
     if (fb->bug_trigger == 0 && strcmp(node, "state") == 0 &&
         xendev->fe_state == XenbusStateConnected &&
         xendev->be_state == XenbusStateConnected) {
-        xen_be_printf(xendev, 2, "re-trigger connected (frontend bug)\n");
+        XEN_BE_LOG(xendev, 2, "re-trigger connected (frontend bug)\n");
         xen_be_set_state(xendev, XenbusStateConnected);
         fb->bug_trigger = 1; /* only once */
     }
diff --git a/src/xenfb_server.c b/src/xenfb_server.c
index 536c5ae..9aee8c4 100644
--- a/src/xenfb_server.c
+++ b/src/xenfb_server.c
@@ -70,7 +70,7 @@ static int common_bind(struct common *c)
 	return -1;
 
     xen_be_bind_evtchn(&c->xendev);
-    xen_be_printf(&c->xendev, 1, "ring ref %d, remote-port %d, local-port %d\n",
+    XEN_BE_LOG(&c->xendev, 1, "ring ref %d, remote-port %d, local-port %d\n",
 		  ref, c->xendev.remote_port, c->xendev.local_port);
 
     return 0;
@@ -350,38 +350,38 @@ static int xenfb_configure_fb(struct XenFB *xenfb, size_t fb_len_lim,
     int max_width, max_height;
 
     if (fb_len_lim > fb_len_max) {
-	xen_be_printf(&xenfb->c.xendev, 0, "fb size limit %zu exceeds %zu, corrected\n",
+	XEN_BE_LOG(&xenfb->c.xendev, 0, "fb size limit %zu exceeds %zu, corrected\n",
 		      fb_len_lim, fb_len_max);
 	fb_len_lim = fb_len_max;
     }
     if (fb_len_lim && fb_len > fb_len_lim) {
-	xen_be_printf(&xenfb->c.xendev, 0, "frontend fb size %zu limited to %zu\n",
+	XEN_BE_LOG(&xenfb->c.xendev, 0, "frontend fb size %zu limited to %zu\n",
 		      fb_len, fb_len_lim);
 	fb_len = fb_len_lim;
     }
     if (depth != 32) {
-	xen_be_printf(&xenfb->c.xendev, 0, "can't handle frontend fb depth %d\n",
+	XEN_BE_LOG(&xenfb->c.xendev, 0, "can't handle frontend fb depth %d\n",
 		      depth);
 	return -1;
     }
     if (row_stride <= 0 || row_stride > fb_len) {
-	xen_be_printf(&xenfb->c.xendev, 0, "invalid frontend stride %d\n", row_stride);
+	XEN_BE_LOG(&xenfb->c.xendev, 0, "invalid frontend stride %d\n", row_stride);
 	return -1;
     }
     max_width = row_stride / (depth / 8);
     if (width < 0 || width > max_width) {
-	xen_be_printf(&xenfb->c.xendev, 0, "invalid frontend width %d limited to %d\n",
+	XEN_BE_LOG(&xenfb->c.xendev, 0, "invalid frontend width %d limited to %d\n",
 		      width, max_width);
 	width = max_width;
     }
     if (offset < 0 || offset >= fb_len) {
-	xen_be_printf(&xenfb->c.xendev, 0, "invalid frontend offset %d (max %zu)\n",
+	XEN_BE_LOG(&xenfb->c.xendev, 0, "invalid frontend offset %d (max %zu)\n",
 		      offset, fb_len - 1);
 	return -1;
     }
     max_height = (fb_len - offset) / row_stride;
     if (height < 0 || height > max_height) {
-	xen_be_printf(&xenfb->c.xendev, 0, "invalid frontend height %d limited to %d\n",
+	XEN_BE_LOG(&xenfb->c.xendev, 0, "invalid frontend height %d limited to %d\n",
 		      height, max_height);
 	height = max_height;
     }
@@ -393,7 +393,7 @@ static int xenfb_configure_fb(struct XenFB *xenfb, size_t fb_len_lim,
     xenfb->offset = offset;
     xenfb->up_fullscreen = 1;
     xenfb->do_resize = 1;
-    xen_be_printf(&xenfb->c.xendev, 1, "framebuffer %dx%dx%d offset %d stride %d\n",
+    XEN_BE_LOG(&xenfb->c.xendev, 1, "framebuffer %dx%dx%d offset %d stride %d\n",
 		  width, height, depth, offset, row_stride);
     return 0;
 }
@@ -469,7 +469,7 @@ static void xenfb_update(void *opaque)
 	if (xenfb->refresh_period != period) {
 	    xenfb_send_refresh_period(xenfb, period);
 	    xenfb->refresh_period = period;
-            xen_be_printf(&xenfb->c.xendev, 1, "refresh period: %d\n", period);
+            XEN_BE_LOG(&xenfb->c.xendev, 1, "refresh period: %d\n", period);
 	}
 #else
 	; /* nothing */
@@ -489,10 +489,10 @@ static void xenfb_update(void *opaque)
 
     /* run queued updates */
     if (xenfb->up_fullscreen) {
-	xen_be_printf(&xenfb->c.xendev, 3, "update: fullscreen\n");
+	XEN_BE_LOG(&xenfb->c.xendev, 3, "update: fullscreen\n");
 	xen_linpicker_fb_update(xenfb, 0, 0, xenfb->width, xenfb->height);
     } else if (xenfb->up_count) {
-	xen_be_printf(&xenfb->c.xendev, 3, "update: %d rects\n", xenfb->up_count);
+	XEN_BE_LOG(&xenfb->c.xendev, 3, "update: %d rects\n", xenfb->up_count);
 	for (i = 0; i < xenfb->up_count; i++)
 	    xen_linpicker_fb_update(xenfb,
 				    xenfb->up_rects[i].x,
@@ -500,7 +500,7 @@ static void xenfb_update(void *opaque)
 				    xenfb->up_rects[i].w,
 				    xenfb->up_rects[i].h);
     } else {
-	xen_be_printf(&xenfb->c.xendev, 3, "update: nothing\n");
+	XEN_BE_LOG(&xenfb->c.xendev, 3, "update: nothing\n");
     }
     xenfb->up_count = 0;
     xenfb->up_fullscreen = 0;
@@ -537,14 +537,14 @@ static void xenfb_handle_events(struct XenFB *xenfb)
 	    w = MIN(event->update.width, xenfb->width - x);
 	    h = MIN(event->update.height, xenfb->height - y);
 	    if (w < 0 || h < 0) {
-                xen_be_printf(&xenfb->c.xendev, 1, "bogus update ignored\n");
+                XEN_BE_LOG(&xenfb->c.xendev, 1, "bogus update ignored\n");
 		break;
 	    }
 	    if (x != event->update.x ||
                 y != event->update.y ||
 		w != event->update.width ||
 		h != event->update.height) {
-                xen_be_printf(&xenfb->c.xendev, 1, "bogus update clipped\n");
+                XEN_BE_LOG(&xenfb->c.xendev, 1, "bogus update clipped\n");
 	    }
 	    if (w == xenfb->width && h > xenfb->height / 2) {
 		/* scroll detector: updated more than 50% of the lines,
@@ -626,7 +626,7 @@ static int fb_initialise(struct XenDevice *xendev)
     if (xenstore_read_fe_int(xendev, "feature-update", &fb->feature_update) == -1)
 	fb->feature_update = 0;
 
-    xen_be_printf(xendev, 1, "feature-update=%d, videoram=%d\n",
+    XEN_BE_LOG(xendev, 1, "feature-update=%d, videoram=%d\n",
 		  fb->feature_update, videoram);
     return xen_linpicker_fb_connect(fb);
 }