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Date: Wed, 18 Apr 2012 14:19:04 -0400
From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To: linux-kernel@...r.kernel.org, xen-devel@...ts.xensource.com,
Stefano Stabellini <stefano.stabellini@...citrix.com>,
Ian.Campbell@...rix.com
Cc: konrad <konrad@...alhost.localdomain>,
Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
konrad.wilk@...cle.com
Subject: [PATCH] xen/xenbus: Add quirk to deal with misconfigured backends.
From: konrad <konrad@...alhost.localdomain>
A rather annoying and common case is when booting a PVonHVM guest
and exposing the PV KBD and PV VFB - as both of those do not
make any sense. The HVM guest is using the VGA driver and the emulated
keyboard for this. So we provide a very basic quirk framework
(can be expanded in the future) to not wait for 6 minutes for those devices
to initialize - they never wont.
To trigger this, put this in your guest config:
vfb = [ 'vnc=1, vnclisten=0.0.0.0 ,vncunused=1']
instead of this:
vnc=1
vnclisten="0.0.0.0"
[v3: Split delay in non-essential (30 seconds) and essential
devices per Ian and Stefano suggestion]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>quirk
---
drivers/xen/xenbus/xenbus_probe_frontend.c | 69 +++++++++++++++++++++------
1 files changed, 53 insertions(+), 16 deletions(-)
diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c b/drivers/xen/xenbus/xenbus_probe_frontend.c
index f20c5f1..7422913 100644
--- a/drivers/xen/xenbus/xenbus_probe_frontend.c
+++ b/drivers/xen/xenbus/xenbus_probe_frontend.c
@@ -135,7 +135,7 @@ static int read_backend_details(struct xenbus_device *xendev)
return xenbus_read_otherend_details(xendev, "backend-id", "backend");
}
-static int is_device_connecting(struct device *dev, void *data)
+static int is_device_connecting(struct device *dev, void *data, bool ignore_vkbd)
{
struct xenbus_device *xendev = to_xenbus_device(dev);
struct device_driver *drv = data;
@@ -152,16 +152,41 @@ static int is_device_connecting(struct device *dev, void *data)
if (drv && (dev->driver != drv))
return 0;
+ if (ignore_vkbd) {
+ /* With older QEMU, for PVonHVM guests the guest config files
+ * could contain: vfb = [ 'vnc=1, vnclisten=0.0.0.0']
+ * which is nonsensical as there is no PV FB (there can be
+ * a PVKB) running as HVM guest. */
+
+ if ((strncmp(xendev->nodename, "device/vkbd", 11) == 0))
+ return 0;
+
+ if ((strncmp(xendev->nodename, "device/vfb", 10) == 0))
+ return 0;
+ }
xendrv = to_xenbus_driver(dev->driver);
return (xendev->state < XenbusStateConnected ||
(xendev->state == XenbusStateConnected &&
xendrv->is_ready && !xendrv->is_ready(xendev)));
}
+static int essential_device_connecting(struct device *dev, void *data)
+{
+ return is_device_connecting(dev, data, true /* ignore PVKB+PVDB */);
+}
+static int non_essential_device_connecting(struct device *dev, void *data)
+{
+ return is_device_connecting(dev, data, false);
+}
-static int exists_connecting_device(struct device_driver *drv)
+static int exists_essential_connecting_device(struct device_driver *drv)
{
return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
- is_device_connecting);
+ essential_device_connecting);
+}
+static int exists_non_essential_connecting_device(struct device_driver *drv)
+{
+ return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
+ non_essential_device_connecting);
}
static int print_device_status(struct device *dev, void *data)
@@ -192,6 +217,23 @@ static int print_device_status(struct device *dev, void *data)
/* We only wait for device setup after most initcalls have run. */
static int ready_to_wait_for_devices;
+static bool wait_loop(unsigned long start, unsigned int max_delay,
+ unsigned int *seconds_waited)
+{
+ if (time_after(jiffies, start + (*seconds_waited+5)*HZ)) {
+ if (!*seconds_waited)
+ printk(KERN_WARNING "XENBUS: Waiting for "
+ "devices to initialise: ");
+ *seconds_waited += 5;
+ printk("%us...", max_delay - *seconds_waited);
+ if (*seconds_waited == max_delay)
+ return true;
+ }
+
+ schedule_timeout_interruptible(HZ/10);
+
+ return false;
+}
/*
* On a 5-minute timeout, wait for all devices currently configured. We need
* to do this to guarantee that the filesystems and / or network devices
@@ -215,19 +257,14 @@ static void wait_for_devices(struct xenbus_driver *xendrv)
if (!ready_to_wait_for_devices || !xen_domain())
return;
- while (exists_connecting_device(drv)) {
- if (time_after(jiffies, start + (seconds_waited+5)*HZ)) {
- if (!seconds_waited)
- printk(KERN_WARNING "XENBUS: Waiting for "
- "devices to initialise: ");
- seconds_waited += 5;
- printk("%us...", 300 - seconds_waited);
- if (seconds_waited == 300)
- break;
- }
-
- schedule_timeout_interruptible(HZ/10);
- }
+ while (exists_non_essential_connecting_device(drv))
+ if (wait_loop(start, 30, &seconds_waited))
+ break;
+
+ /* Skips PVKB and PVFB check.*/
+ while (exists_essential_connecting_device(drv))
+ if (wait_loop(start, 270, &seconds_waited))
+ break;
if (seconds_waited)
printk("\n");
--
1.7.7.5
--
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