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Re: [Xen-devel] [PATCH for-4.13] xen/arm: fix duplicate memory node in DT



Hi,

On 05/10/2019 00:09, Stefano Stabellini wrote:
When reserved-memory regions are present in the host device tree, dom0
is started with multiple memory nodes. Each memory node should have a
unique name, but today they are all called "memory" leading to Linux
printing the following warning at boot:

   OF: Duplicate name in base, renamed to "memory#1"

This patch fixes the problem by appending a "@<unit-address>" to the
name, as per the Device Tree specification, where <unit-address> matches
the base of address of the first region.

Reported-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>

---

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 921b054520..a4c07db383 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -646,16 +646,22 @@ static int __init make_memory_node(const struct domain *d,
      int res, i;
      int reg_size = addrcells + sizecells;
      int nr_cells = reg_size * mem->nr_banks;
+    /* Placeholder for memory@ + a 32-bit number + \0 */
+    char buf[18];
      __be32 reg[NR_MEM_BANKS * 4 /* Worst case addrcells + sizecells */];
      __be32 *cells;
BUG_ON(nr_cells >= ARRAY_SIZE(reg));
+    /* Nothing to do */

This a departure from the current solution where a node will be created with no "reg" property. I think this change of behavior should at least be described in the commit message if not implemented in a separate patch. But...

+    if ( mem->nr_banks == 0 )
+        return 0;

... I don't think we want to ignore it. The caller most likely messed up the banks and we should instead report an error.

dt_dprintk("Create memory node (reg size %d, nr cells %d)\n",
                 reg_size, nr_cells);
/* ePAPR 3.4 */
-    res = fdt_begin_node(fdt, "memory");
+    snprintf(buf, sizeof(buf), "memory@%"PRIx64, mem->bank[0].start);
+    res = fdt_begin_node(fdt, buf);
      if ( res )
          return res;

Cheers,

--
Julien Grall

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