Check RAM availability before VM is initialized.

Quite often (especially on older XP machines) attempts to allocate large VM RAM is
going to fail, and crash the emulator. Since it's failing deep inside QEMU, it's
not really possible to provide the user with a meaningful explanation for the crash.
So, before initializing VM we should check if QEMU is going to be able to allocate
requested amount of RAM, and if not, try to come up with a recomendation.

Change-Id: Id6213d50c70f6bd3b32c4df2ded96d8e3013ec40

1 files changed, 26 insertions, 0 deletions

diff --git a/vl-android.c b/vl-android.c
index f9afa5c..7b661b6 100644
--- a/vl-android.c
+++ b/vl-android.c
@@ -4046,6 +4046,32 @@ int main(int argc, char **argv, char **envp)
         }
     }
 
+    /* Quite often (especially on older XP machines) attempts to allocate large
+     * VM RAM is going to fail, and crash the emulator. Since it's failing deep
+     * inside QEMU, it's not really possible to provide the user with a
+     * meaningful explanation for the crash. So, lets see if QEMU is going to be
+     * able to allocate requested amount of RAM, and if not, lets try to come up
+     * with a recomendation. */
+    {
+        ram_addr_t r_ram = ram_size;
+        void* alloc_check = malloc(r_ram);
+        while (alloc_check == NULL && r_ram > 1024 * 1024) {
+        /* Make it 25% less */
+            r_ram -= r_ram / 4;
+            alloc_check = malloc(r_ram);
+        }
+        if (alloc_check != NULL) {
+            free(alloc_check);
+        }
+        if (r_ram != ram_size) {
+            /* Requested RAM is too large. Report this, as well as calculated
+             * recomendation. */
+            dwarning("Requested RAM size of %dMB is too large for your environment, and is reduced to %dMB.",
+                     (int)(ram_size / 1024 / 1024), (int)(r_ram / 1024 / 1024));
+            ram_size = r_ram;
+        }
+    }
+
 #ifdef CONFIG_KQEMU
     /* FIXME: This is a nasty hack because kqemu can't cope with dynamic
        guest ram allocation.  It needs to go away.  */