From: Penny Zheng
This commit describe the new scenario where host address is not provided
in "xen,shared-mem" property and a new example is added to the page to
explain in details.
Take the occasion to fix some typos in the page.
Signed-off-by: Penny Zheng
Signed-off-by: Luca Fancellu
---
v1:
- patch from
https://patchwork.kernel.org/project/xen-devel/patch/20231206090623.1932275-10-penny.zh...@arm.com/
with some changes in the commit message.
---
docs/misc/arm/device-tree/booting.txt | 52 ---
1 file changed, 39 insertions(+), 13 deletions(-)
diff --git a/docs/misc/arm/device-tree/booting.txt
b/docs/misc/arm/device-tree/booting.txt
index bbd955e9c2f6..ac4bad6fe5e0 100644
--- a/docs/misc/arm/device-tree/booting.txt
+++ b/docs/misc/arm/device-tree/booting.txt
@@ -590,7 +590,7 @@ communication.
An array takes a physical address, which is the base address of the
shared memory region in host physical address space, a size, and a guest
physical address, as the target address of the mapping.
-e.g. xen,shared-mem = < [host physical address] [guest address] [size] >
+e.g. xen,shared-mem = < [host physical address] [guest address] [size] >;
It shall also meet the following criteria:
1) If the SHM ID matches with an existing region, the address range of the
@@ -601,8 +601,8 @@ communication.
The number of cells for the host address (and size) is the same as the
guest pseudo-physical address and they are inherited from the parent node.
-Host physical address is optional, when missing Xen decides the location
-(currently unimplemented).
+Host physical address is optional, when missing Xen decides the location.
+e.g. xen,shared-mem = < [guest address] [size] >;
- role (Optional)
@@ -629,7 +629,7 @@ chosen {
role = "owner";
xen,shm-id = "my-shared-mem-0";
xen,shared-mem = <0x1000 0x1000 0x1000>;
-}
+};
domU1 {
compatible = "xen,domain";
@@ -640,25 +640,36 @@ chosen {
vpl011;
/*
- * shared memory region identified as 0x0(xen,shm-id = <0x0>)
- * is shared between Dom0 and DomU1.
+ * shared memory region "my-shared-mem-0" is shared
+ * between Dom0 and DomU1.
*/
domU1-shared-mem@1000 {
compatible = "xen,domain-shared-memory-v1";
role = "borrower";
xen,shm-id = "my-shared-mem-0";
xen,shared-mem = <0x1000 0x5000 0x1000>;
-}
+};
/*
- * shared memory region identified as 0x1(xen,shm-id = <0x1>)
- * is shared between DomU1 and DomU2.
+ * shared memory region "my-shared-mem-1" is shared between
+ * DomU1 and DomU2.
*/
domU1-shared-mem@5000 {
compatible = "xen,domain-shared-memory-v1";
xen,shm-id = "my-shared-mem-1";
xen,shared-mem = <0x5000 0x6000 0x2000>;
-}
+};
+
+/*
+ * shared memory region "my-shared-mem-2" is shared between
+ * DomU1 and DomU2.
+ */
+domU1-shared-mem-2 {
+compatible = "xen,domain-shared-memory-v1";
+xen,shm-id = "my-shared-mem-2";
+role = "owner";
+xen,shared-mem = <0x8000 0x2000>;
+};
..
@@ -672,14 +683,21 @@ chosen {
cpus = <1>;
/*
- * shared memory region identified as 0x1(xen,shm-id = <0x1>)
- * is shared between domU1 and domU2.
+ * shared memory region "my-shared-mem-1" is shared between
+ * domU1 and domU2.
*/
domU2-shared-mem@5000 {
compatible = "xen,domain-shared-memory-v1";
xen,shm-id = "my-shared-mem-1";
xen,shared-mem = <0x5000 0x7000 0x2000>;
-}
+};
+
+domU2-shared-mem-2 {
+compatible = "xen,domain-shared-memory-v1";
+xen,shm-id = "my-shared-mem-2";
+role = "borrower";
+xen,shared-mem = <0x9000 0x2000>;
+};
..
};
@@ -699,3 +717,11 @@ shared between DomU1 and DomU2. It will get mapped at
0x6000 in DomU1 guest
physical address space, and at 0x7000 in DomU2 guest physical address
space.
DomU1 and DomU2 are both the borrower domain, the owner domain is the default
owner domain DOMID_IO.
+
+For the static shared memory region "my-shared-mem-2", since host physical
+address is not provided by user, Xen will automatically allocate 512MB
+from heap as static shared memory to be shared between DomU1 and DomU2.
+The automatically allocated static shared memory will get mapped at
+0x8000 in DomU1 guest physical address space, and at 0x9000 in DomU2
+guest physical address space. DomU1 is explicitly defined as the owner domain,
+and DomU2 is the borrower domain.
--
2.34.1
