[PATCH v4] xen/arm: warn if dom0_mem is not specified

[Stefano Stabellini <sstabellini@kernel.org>]

The default dom0_mem is 128M which is not sufficient to boot a Ubuntu
based Dom0. It is not clear what a better default value could be.

Instead, loudly warn the user when dom0_mem is unspecified and wait 3
secs. Then use 512M.

Update the docs to specify that dom0_mem is required on ARM. (The
current xen-command-line document does not actually reflect the current
behavior of dom0_mem on ARM correctly.)

Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
---
Changes in v4:
- use warning_add

Changes in v3:
- update docs
---
 docs/misc/xen-command-line.markdown |  8 +++++++-
 xen/arch/arm/domain_build.c         | 15 ++++++++++-----
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/docs/misc/xen-command-line.markdown b/docs/misc/xen-command-line.markdown
index a11fdf9..c0106fb 100644
--- a/docs/misc/xen-command-line.markdown
+++ b/docs/misc/xen-command-line.markdown
@@ -603,7 +603,13 @@ For example, with `dom0_max_vcpus=4-8`:
 >      8    |  8
 >     10    |  8
 
-### dom0\_mem
+### dom0\_mem (ARM)
+> `= <size>`
+
+Set the amount of memory for the initial domain (dom0). It must be
+greater than zero. This parameter is required.
+
+### dom0\_mem (x86)
 > `= List of ( min:<size> | max:<size> | <size> )`
 
 Set the amount of memory for the initial domain (dom0). If a size is
diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index c97a1f5..7949b2b 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -13,6 +13,7 @@
 #include <xen/guest_access.h>
 #include <xen/iocap.h>
 #include <xen/acpi.h>
+#include <xen/warning.h>
 #include <acpi/actables.h>
 #include <asm/device.h>
 #include <asm/setup.h>
@@ -31,14 +32,11 @@ integer_param("dom0_max_vcpus", opt_dom0_max_vcpus);
 
 int dom0_11_mapping = 1;
 
-#define DOM0_MEM_DEFAULT 0x8000000 /* 128 MiB */
-static u64 __initdata dom0_mem = DOM0_MEM_DEFAULT;
+static u64 __initdata dom0_mem;
 
 static void __init parse_dom0_mem(const char *s)
 {
     dom0_mem = parse_size_and_unit(s, &s);
-    if ( dom0_mem == 0 )
-        dom0_mem = DOM0_MEM_DEFAULT;
 }
 custom_param("dom0_mem", parse_dom0_mem);
 
@@ -2125,7 +2123,14 @@ int construct_dom0(struct domain *d)
     BUG_ON(d->vcpu[0] == NULL);
     BUG_ON(v->is_initialised);
 
-    printk("*** LOADING DOMAIN 0 ***\n");
+    if ( dom0_mem > 0 )
+        printk("*** LOADING DOMAIN 0 ***\n");
+    else
+    {
+        warning_add("PLEASE SPECIFY dom0_mem PARAMETER - USING 512M FOR NOW\n");
+        dom0_mem = MB(512);
+    }
+
 
     iommu_hwdom_init(d);
 
-- 
1.9.1


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