hw/arm/boot: Don't set up ATAGS for autogenerated dtb booting

The code which decides whether to set up the ATAGS data structure on
reset was using the wrong conditional, which meant we were creating
an ATAGS structure when doing a device-tree boot if the dtb was
autogenerated by the board. This is harmless, but unnecessary, so
bring it in to line with user-provided-dtb boots.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Message-id: 1388326833-656-1-git-send-email-peter.maydell@linaro.org
diff --git a/hw/arm/boot.c b/hw/arm/boot.c
index 1c1b0e5..4036262 100644
--- a/hw/arm/boot.c
+++ b/hw/arm/boot.c
@@ -173,6 +173,11 @@
     env->regs[15] = info->smp_loader_start;
 }
 
+static inline bool have_dtb(const struct arm_boot_info *info)
+{
+    return info->dtb_filename || info->get_dtb;
+}
+
 #define WRITE_WORD(p, value) do { \
     stl_phys_notdirty(p, value);  \
     p += 4;                       \
@@ -421,7 +426,7 @@
                     env->regs[15] = info->loader_start;
                 }
 
-                if (!info->dtb_filename) {
+                if (!have_dtb(info)) {
                     if (old_param) {
                         set_kernel_args_old(info);
                     } else {
@@ -542,7 +547,7 @@
         /* for device tree boot, we pass the DTB directly in r2. Otherwise
          * we point to the kernel args.
          */
-        if (info->dtb_filename || info->get_dtb) {
+        if (have_dtb(info)) {
             /* Place the DTB after the initrd in memory. Note that some
              * kernels will trash anything in the 4K page the initrd
              * ends in, so make sure the DTB isn't caught up in that.