mini-os: make frontends and xenbus optional

This adds compile-time logic to disable certain frontends in mini-os:
 - pcifront is disabled by default, enabled for ioemu
 - blkfront, netfront, fbfront, kbdfront, consfront are enabled by default
 - xenbus is required for any frontend, and is enabled by default

If all frontends and xenbus are disabled, mini-os will run without
needing to communicate with xenstore, making it suitable to run the
xenstore daemon. The console frontend is not required for the initial
console, only consoles opened via openpt or ptmx.

Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>

4 files changed, 203 insertions, 185 deletions

diff --git a/extras/mini-os/console/console.c b/extras/mini-os/console/console.c
index 2b4ed9ff44..fec3791c20 100644
--- a/extras/mini-os/console/console.c
+++ b/extras/mini-os/console/console.c
@@ -158,8 +158,3 @@ void init_console(void)
     /* This is also required to notify the daemon */
     printk("done.\n");
 }
-
-void fini_console(struct consfront_dev *dev)
-{
-    if (dev) free_consfront(dev);
-}
diff --git a/extras/mini-os/console/console.h b/extras/mini-os/console/console.h
new file mode 100644
index 0000000000..e85147a4ba
--- /dev/null
+++ b/extras/mini-os/console/console.h
@@ -0,0 +1,2 @@
+
+void console_handle_input(evtchn_port_t port, struct pt_regs *regs, void *data);
diff --git a/extras/mini-os/console/xenbus.c b/extras/mini-os/console/xenbus.c
new file mode 100644
index 0000000000..77de82a0fa
--- /dev/null
+++ b/extras/mini-os/console/xenbus.c
@@ -0,0 +1,198 @@
+#include <mini-os/types.h>
+#include <mini-os/wait.h>
+#include <mini-os/mm.h>
+#include <mini-os/hypervisor.h>
+#include <mini-os/events.h>
+#include <mini-os/os.h>
+#include <mini-os/lib.h>
+#include <mini-os/xenbus.h>
+#include <xen/io/console.h>
+#include <xen/io/protocols.h>
+#include <xen/io/ring.h>
+#include <mini-os/xmalloc.h>
+#include <mini-os/gnttab.h>
+#include "console.h"
+
+void free_consfront(struct consfront_dev *dev)
+{
+    char* err = NULL;
+    XenbusState state;
+
+    char path[strlen(dev->backend) + 1 + 5 + 1];
+    char nodename[strlen(dev->nodename) + 1 + 5 + 1];
+
+    snprintf(path, sizeof(path), "%s/state", dev->backend);
+    snprintf(nodename, sizeof(nodename), "%s/state", dev->nodename);
+
+    if ((err = xenbus_switch_state(XBT_NIL, nodename, XenbusStateClosing)) != NULL) {
+        printk("free_consfront: error changing state to %d: %s\n",
+                XenbusStateClosing, err);
+        goto close;
+    }
+    state = xenbus_read_integer(path);
+    while (err == NULL && state < XenbusStateClosing)
+        err = xenbus_wait_for_state_change(path, &state, &dev->events);
+    if (err) free(err);
+
+    if ((err = xenbus_switch_state(XBT_NIL, nodename, XenbusStateClosed)) != NULL) {
+        printk("free_consfront: error changing state to %d: %s\n",
+                XenbusStateClosed, err);
+        goto close;
+    }
+
+close:
+    if (err) free(err);
+    xenbus_unwatch_path_token(XBT_NIL, path, path);
+
+    mask_evtchn(dev->evtchn);
+    unbind_evtchn(dev->evtchn);
+    free(dev->backend);
+    free(dev->nodename);
+
+    gnttab_end_access(dev->ring_ref);
+
+    free_page(dev->ring);
+    free(dev);
+}
+
+struct consfront_dev *init_consfront(char *_nodename)
+{
+    xenbus_transaction_t xbt;
+    char* err;
+    char* message=NULL;
+    int retry=0;
+    char* msg = NULL;
+    char nodename[256];
+    char path[256];
+    static int consfrontends = 3;
+    struct consfront_dev *dev;
+    int res;
+
+    if (!_nodename)
+        snprintf(nodename, sizeof(nodename), "device/console/%d", consfrontends);
+    else
+        strncpy(nodename, _nodename, sizeof(nodename));
+
+    printk("******************* CONSFRONT for %s **********\n\n\n", nodename);
+
+    consfrontends++;
+    dev = malloc(sizeof(*dev));
+    memset(dev, 0, sizeof(*dev));
+    dev->nodename = strdup(nodename);
+#ifdef HAVE_LIBC
+    dev->fd = -1;
+#endif
+
+    snprintf(path, sizeof(path), "%s/backend-id", nodename);
+    if ((res = xenbus_read_integer(path)) < 0) 
+        return NULL;
+    else
+        dev->dom = res;
+    evtchn_alloc_unbound(dev->dom, console_handle_input, dev, &dev->evtchn);
+
+    dev->ring = (struct xencons_interface *) alloc_page();
+    memset(dev->ring, 0, PAGE_SIZE);
+    dev->ring_ref = gnttab_grant_access(dev->dom, virt_to_mfn(dev->ring), 0);
+
+    dev->events = NULL;
+
+again:
+    err = xenbus_transaction_start(&xbt);
+    if (err) {
+        printk("starting transaction\n");
+        free(err);
+    }
+
+    err = xenbus_printf(xbt, nodename, "ring-ref","%u",
+                dev->ring_ref);
+    if (err) {
+        message = "writing ring-ref";
+        goto abort_transaction;
+    }
+    err = xenbus_printf(xbt, nodename,
+                "port", "%u", dev->evtchn);
+    if (err) {
+        message = "writing event-channel";
+        goto abort_transaction;
+    }
+    err = xenbus_printf(xbt, nodename,
+                "protocol", "%s", XEN_IO_PROTO_ABI_NATIVE);
+    if (err) {
+        message = "writing protocol";
+        goto abort_transaction;
+    }
+
+    err = xenbus_printf(xbt, nodename, "type", "%s", "ioemu");
+    if (err) {
+        message = "writing type";
+        goto abort_transaction;
+    }
+
+    snprintf(path, sizeof(path), "%s/state", nodename);
+    err = xenbus_switch_state(xbt, path, XenbusStateConnected);
+    if (err) {
+        message = "switching state";
+        goto abort_transaction;
+    }
+
+
+    err = xenbus_transaction_end(xbt, 0, &retry);
+    if (err) free(err);
+    if (retry) {
+            goto again;
+        printk("completing transaction\n");
+    }
+
+    goto done;
+
+abort_transaction:
+    free(err);
+    err = xenbus_transaction_end(xbt, 1, &retry);
+    printk("Abort transaction %s\n", message);
+    goto error;
+
+done:
+
+    snprintf(path, sizeof(path), "%s/backend", nodename);
+    msg = xenbus_read(XBT_NIL, path, &dev->backend);
+    if (msg) {
+        printk("Error %s when reading the backend path %s\n", msg, path);
+        goto error;
+    }
+
+    printk("backend at %s\n", dev->backend);
+
+    {
+        XenbusState state;
+        char path[strlen(dev->backend) + 1 + 19 + 1];
+        snprintf(path, sizeof(path), "%s/state", dev->backend);
+        
+	xenbus_watch_path_token(XBT_NIL, path, path, &dev->events);
+        msg = NULL;
+        state = xenbus_read_integer(path);
+        while (msg == NULL && state < XenbusStateConnected)
+            msg = xenbus_wait_for_state_change(path, &state, &dev->events);
+        if (msg != NULL || state != XenbusStateConnected) {
+            printk("backend not available, state=%d\n", state);
+            xenbus_unwatch_path_token(XBT_NIL, path, path);
+            goto error;
+        }
+    }
+    unmask_evtchn(dev->evtchn);
+
+    printk("**************************\n");
+
+    return dev;
+
+error:
+    free(msg);
+    free(err);
+    free_consfront(dev);
+    return NULL;
+}
+
+void fini_console(struct consfront_dev *dev)
+{
+    if (dev) free_consfront(dev);
+}
+
diff --git a/extras/mini-os/console/xencons_ring.c b/extras/mini-os/console/xencons_ring.c
index 8b81dc41ae..81c8e997a9 100644
--- a/extras/mini-os/console/xencons_ring.c
+++ b/extras/mini-os/console/xencons_ring.c
@@ -11,6 +11,7 @@
 #include <xen/io/ring.h>
 #include <mini-os/xmalloc.h>
 #include <mini-os/gnttab.h>
+#include "console.h"
 
 DECLARE_WAIT_QUEUE_HEAD(console_queue);
 
@@ -70,7 +71,7 @@ int xencons_ring_send(struct consfront_dev *dev, const char *data, unsigned len)
 
 
 
-static void handle_input(evtchn_port_t port, struct pt_regs *regs, void *data)
+void console_handle_input(evtchn_port_t port, struct pt_regs *regs, void *data)
 {
 	struct consfront_dev *dev = (struct consfront_dev *) data;
 #ifdef HAVE_LIBC
@@ -173,7 +174,7 @@ struct consfront_dev *xencons_ring_init(void)
 	dev->evtchn = start_info.console.domU.evtchn;
 	dev->ring = (struct xencons_interface *) mfn_to_virt(start_info.console.domU.mfn);
 
-	err = bind_evtchn(dev->evtchn, handle_input, dev);
+	err = bind_evtchn(dev->evtchn, console_handle_input, dev);
 	if (err <= 0) {
 		printk("XEN console request chn bind failed %i\n", err);
                 free(dev);
@@ -187,184 +188,6 @@ struct consfront_dev *xencons_ring_init(void)
 	return dev;
 }
 
-void free_consfront(struct consfront_dev *dev)
-{
-    char* err = NULL;
-    XenbusState state;
-
-    char path[strlen(dev->backend) + 1 + 5 + 1];
-    char nodename[strlen(dev->nodename) + 1 + 5 + 1];
-
-    snprintf(path, sizeof(path), "%s/state", dev->backend);
-    snprintf(nodename, sizeof(nodename), "%s/state", dev->nodename);
-
-    if ((err = xenbus_switch_state(XBT_NIL, nodename, XenbusStateClosing)) != NULL) {
-        printk("free_consfront: error changing state to %d: %s\n",
-                XenbusStateClosing, err);
-        goto close;
-    }
-    state = xenbus_read_integer(path);
-    while (err == NULL && state < XenbusStateClosing)
-        err = xenbus_wait_for_state_change(path, &state, &dev->events);
-    if (err) free(err);
-
-    if ((err = xenbus_switch_state(XBT_NIL, nodename, XenbusStateClosed)) != NULL) {
-        printk("free_consfront: error changing state to %d: %s\n",
-                XenbusStateClosed, err);
-        goto close;
-    }
-
-close:
-    if (err) free(err);
-    xenbus_unwatch_path_token(XBT_NIL, path, path);
-
-    mask_evtchn(dev->evtchn);
-    unbind_evtchn(dev->evtchn);
-    free(dev->backend);
-    free(dev->nodename);
-
-    gnttab_end_access(dev->ring_ref);
-
-    free_page(dev->ring);
-    free(dev);
-}
-
-struct consfront_dev *init_consfront(char *_nodename)
-{
-    xenbus_transaction_t xbt;
-    char* err;
-    char* message=NULL;
-    int retry=0;
-    char* msg = NULL;
-    char nodename[256];
-    char path[256];
-    static int consfrontends = 3;
-    struct consfront_dev *dev;
-    int res;
-
-    if (!_nodename)
-        snprintf(nodename, sizeof(nodename), "device/console/%d", consfrontends);
-    else
-        strncpy(nodename, _nodename, sizeof(nodename));
-
-    printk("******************* CONSFRONT for %s **********\n\n\n", nodename);
-
-    consfrontends++;
-    dev = malloc(sizeof(*dev));
-    memset(dev, 0, sizeof(*dev));
-    dev->nodename = strdup(nodename);
-#ifdef HAVE_LIBC
-    dev->fd = -1;
-#endif
-
-    snprintf(path, sizeof(path), "%s/backend-id", nodename);
-    if ((res = xenbus_read_integer(path)) < 0) 
-        return NULL;
-    else
-        dev->dom = res;
-    evtchn_alloc_unbound(dev->dom, handle_input, dev, &dev->evtchn);
-
-    dev->ring = (struct xencons_interface *) alloc_page();
-    memset(dev->ring, 0, PAGE_SIZE);
-    dev->ring_ref = gnttab_grant_access(dev->dom, virt_to_mfn(dev->ring), 0);
-
-    dev->events = NULL;
-
-again:
-    err = xenbus_transaction_start(&xbt);
-    if (err) {
-        printk("starting transaction\n");
-        free(err);
-    }
-
-    err = xenbus_printf(xbt, nodename, "ring-ref","%u",
-                dev->ring_ref);
-    if (err) {
-        message = "writing ring-ref";
-        goto abort_transaction;
-    }
-    err = xenbus_printf(xbt, nodename,
-                "port", "%u", dev->evtchn);
-    if (err) {
-        message = "writing event-channel";
-        goto abort_transaction;
-    }
-    err = xenbus_printf(xbt, nodename,
-                "protocol", "%s", XEN_IO_PROTO_ABI_NATIVE);
-    if (err) {
-        message = "writing protocol";
-        goto abort_transaction;
-    }
-
-    err = xenbus_printf(xbt, nodename, "type", "%s", "ioemu");
-    if (err) {
-        message = "writing type";
-        goto abort_transaction;
-    }
-
-    snprintf(path, sizeof(path), "%s/state", nodename);
-    err = xenbus_switch_state(xbt, path, XenbusStateConnected);
-    if (err) {
-        message = "switching state";
-        goto abort_transaction;
-    }
-
-
-    err = xenbus_transaction_end(xbt, 0, &retry);
-    if (err) free(err);
-    if (retry) {
-            goto again;
-        printk("completing transaction\n");
-    }
-
-    goto done;
-
-abort_transaction:
-    free(err);
-    err = xenbus_transaction_end(xbt, 1, &retry);
-    printk("Abort transaction %s\n", message);
-    goto error;
-
-done:
-
-    snprintf(path, sizeof(path), "%s/backend", nodename);
-    msg = xenbus_read(XBT_NIL, path, &dev->backend);
-    if (msg) {
-        printk("Error %s when reading the backend path %s\n", msg, path);
-        goto error;
-    }
-
-    printk("backend at %s\n", dev->backend);
-
-    {
-        XenbusState state;
-        char path[strlen(dev->backend) + 1 + 19 + 1];
-        snprintf(path, sizeof(path), "%s/state", dev->backend);
-        
-	xenbus_watch_path_token(XBT_NIL, path, path, &dev->events);
-        msg = NULL;
-        state = xenbus_read_integer(path);
-        while (msg == NULL && state < XenbusStateConnected)
-            msg = xenbus_wait_for_state_change(path, &state, &dev->events);
-        if (msg != NULL || state != XenbusStateConnected) {
-            printk("backend not available, state=%d\n", state);
-            xenbus_unwatch_path_token(XBT_NIL, path, path);
-            goto error;
-        }
-    }
-    unmask_evtchn(dev->evtchn);
-
-    printk("**************************\n");
-
-    return dev;
-
-error:
-    free(msg);
-    free(err);
-    free_consfront(dev);
-    return NULL;
-}
-
 void xencons_resume(void)
 {
 	(void)xencons_ring_init();