On Fri, 2012-07-27 at 15:48 +0100, Stefano Stabellini wrote:

On Fri, 27 Jul 2012, Ian Campbell wrote:

quoted

On Thu, 2012-07-26 at 16:33 +0100, Stefano Stabellini wrote:

quoted

Check for a "/xen" node in the device tree, if it is present set
xen_domain_type to XEN_HVM_DOMAIN and continue initialization.

Map the real shared info page using XENMEM_add_to_physmap with
XENMAPSPACE_shared_info.

Signed-off-by: Stefano Stabellini <redacted>
---
 arch/arm/xen/enlighten.c |   56 ++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 56 insertions(+), 0 deletions(-)

diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index d27c2a6..8c923af 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c

@@ -5,6 +5,9 @@
 #include <asm/xen/hypervisor.h>
 #include <asm/xen/hypercall.h>
 #include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
 
 struct start_info _xen_start_info;
 struct start_info *xen_start_info = &_xen_start_info;

@@ -33,3 +36,56 @@ int xen_remap_domain_mfn_range(struct vm_area_struct *vma,
 	return -ENOSYS;
 }
 EXPORT_SYMBOL_GPL(xen_remap_domain_mfn_range);
+
+/*
+ * == Xen Device Tree format ==
+ * - /xen node;
+ * - compatible "arm,xen";
+ * - one interrupt for Xen event notifications;
+ * - one memory region to map the grant_table.
+ */
+static int __init xen_guest_init(void)
+{
+	int cpu;
+	struct xen_add_to_physmap xatp;
+	static struct shared_info *shared_info_page = 0;
+	struct device_node *node;
+
+	node = of_find_compatible_node(NULL, NULL, "arm,xen");
+	if (!node) {
+		pr_info("No Xen support\n");
+		return 0;
+	}

This should either only print in the success case (to avoid spamming
everyone) or we need a little bit of infrastructure like on x86 so that
we print exactly one of:
	"Booting natively on bearmetal"
	"Booting paravirtualised on %s", hypervisor->name

This function is only going to be called once (actually it might be
called twice with the change introduced by "xen/arm: Introduce
xen_guest_init").

Once (or twice), per boot, per ARM system running Linux in the world...

Ian.