[Qemu-devel] [PATCH 1/2] Allow boards to specify maximum RAM size

[Peter Maydell]

Allow boards to specify their maximum RAM size in the QEMUMachine struct.
This allows us to provide a useful diagnostic if the user tries to specify
a RAM size that the board cannot support.

Signed-off-by: Peter Maydell <address@hidden>
---
 hw/boards.h |    1 +
 vl.c        |   16 +++++++++++++++-
 2 files changed, 16 insertions(+), 1 deletions(-)

diff --git a/hw/boards.h b/hw/boards.h
index 6f0f0d7..bf63f8d 100644
--- a/hw/boards.h
+++ b/hw/boards.h
@@ -19,6 +19,7 @@ typedef struct QEMUMachine {
     QEMUMachineInitFunc *init;
     int use_scsi;
     int max_cpus;
+    ram_addr_t max_ram;
     unsigned int no_serial:1,
         no_parallel:1,
         use_virtcon:1,
diff --git a/vl.c b/vl.c
index b1a94aa..971ad90 100644
--- a/vl.c
+++ b/vl.c
@@ -166,6 +166,9 @@ int main(int argc, char **argv)
 //#define DEBUG_NET
 //#define DEBUG_SLIRP
 
+/* Note that this default RAM size is capped to any maximum
+ * RAM size specified in the board's QEMUMachine struct.
+ */
 #define DEFAULT_RAM_SIZE 128
 
 #define MAX_VIRTIO_CONSOLES 1
@@ -2910,8 +2913,19 @@ int main(int argc, char **argv, char **envp)
         exit(1);
 
     /* init the memory */
-    if (ram_size == 0)
+    if (ram_size == 0) {
         ram_size = DEFAULT_RAM_SIZE * 1024 * 1024;
+        if (machine->max_ram) {
+            ram_size = MIN(ram_size, machine->max_ram);
+        }
+    } else if (machine->max_ram && ram_size > machine->max_ram) {
+        /* Since you can only specify ram_size on the command line in MB it's
+         * OK to round down when printing the machine's maximum.
+         */
+        fprintf(stderr, "qemu: maximum permitted RAM size for '%s' is %ldM\n",
+                machine->name, (machine->max_ram / (1024 * 1024)));
+        exit(1);
+    }
 
     /* init the dynamic translator */
     cpu_exec_init_all(tb_size * 1024 * 1024);
-- 
1.7.1