[Xen-devel] [PATCH RFC 20/35] xen/arm: Prepare a min DT for DOM0

[parth.dixit@xxxxxxxxxx]

From: Naresh Bhat <naresh.bhat@xxxxxxxxxx>

This patch prepare a DT from scratch for DOM0 for
ACPI-case only. Basically the DT contains minmal
required informations such as DOM0 bootargs, memory
and ACPI RSDP informations only.

Signed-off-by: Naresh Bhat <naresh.bhat@xxxxxxxxxx>
---
 xen/arch/arm/domain_build.c | 67 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 66 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index de180d8..bb7f043 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -18,6 +18,7 @@
 #include <asm/psci.h>
 #include <asm/setup.h>
 #include <asm/cpufeature.h>
+#include <asm/acpi.h>
 
 #include <asm/gic.h>
 #include <xen/irq.h>
@@ -61,6 +62,9 @@ custom_param("dom0_mem", parse_dom0_mem);
  */
 #define DOM0_FDT_EXTRA_SIZE (128 + sizeof(struct fdt_reserve_entry))
 
+/* Reserve DOM0 FDT size in ACPI case only */
+#define DOM0_FDT_MIN_SIZE 4096
+
 struct vcpu *__init alloc_dom0_vcpu0(struct domain *dom0)
 {
     if ( opt_dom0_max_vcpus == 0 )
@@ -1151,6 +1155,63 @@ static int handle_node(struct domain *d, struct 
kernel_info *kinfo,
     return res;
 }
 
+/*
+ * Prepare a minimal DTB for DOM0 which contains
+ * bootargs, memory information,
+ * ACPI RSDP pointer.
+ */
+static int prepare_dtb_acpi(struct domain *d, struct kernel_info *kinfo)
+{
+    int new_size;
+    int ret;
+
+    DPRINT("Prepare a min DTB for DOM0\n");
+
+    /* Allocate min size for DT */
+    new_size = DOM0_FDT_MIN_SIZE;
+    kinfo->fdt = xmalloc_bytes(DOM0_FDT_MIN_SIZE);
+
+    if ( kinfo->fdt == NULL )
+        return -ENOMEM;
+
+    /* Create a new empty DT for DOM0 */
+    ret = fdt_create(kinfo->fdt, new_size);
+    if ( ret < 0 )
+        goto err;
+
+    /* Reserve the memory space for new DT */
+    ret = fdt_finish_reservemap(kinfo->fdt);
+    if ( ret < 0 )
+        goto err;
+
+    ret = fdt_begin_node(kinfo->fdt, "/");
+    if ( ret < 0 )
+        goto err;
+
+    ret = fdt_property_cell(kinfo->fdt, "#address-cells", 2);
+    if ( ret )
+        return ret;
+
+    ret = fdt_property_cell(kinfo->fdt, "#size-cells", 1);
+    if ( ret )
+        return ret;
+
+    ret = fdt_end_node(kinfo->fdt);
+    if ( ret < 0 )
+        goto err;
+
+    ret = fdt_finish(kinfo->fdt);
+    if ( ret < 0 )
+        goto err;
+
+    return 0;
+
+  err:
+    printk("Device tree generation failed (%d).\n", ret);
+    xfree(kinfo->fdt);
+    return -EINVAL;
+}
+
 static int prepare_dtb(struct domain *d, struct kernel_info *kinfo)
 {
     const void *fdt;
@@ -1305,7 +1366,11 @@ int construct_dom0(struct domain *d)
 
     allocate_memory(d, &kinfo);
 
-    rc = prepare_dtb(d, &kinfo);
+    if (acpi_disabled)
+        rc = prepare_dtb(d, &kinfo);
+    else
+        rc = prepare_dtb_acpi(d, &kinfo);
+
     if ( rc < 0 )
         return rc;
 
-- 
1.9.1


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