hw/arm/boot: allow using a command line specified dtb without a kernel

When kernel and device tree are specified in the QEMU commandline, then
this device tree may be modified e.g. to add virtio_mmio devices.
With a bootloader e.g. on a flash device these extra devices are not
available.
With this change, the device tree can be specified at the QEMU commandline.
The modified device tree made available to the bootloader with the same
mechanism already supported by device trees fully generated by QEMU.

Signed-off-by: Michael Olbrich <m.olbrich@pengutronix.de>
Message-id: 1473520054-402-1-git-send-email-m.olbrich@pengutronix.de
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 2 insertions, 7 deletions

diff --git a/hw/arm/boot.c b/hw/arm/boot.c
index 1b913a43ca..942416d95a 100644
--- a/hw/arm/boot.c
+++ b/hw/arm/boot.c
@@ -773,6 +773,8 @@ static void arm_load_kernel_notify(Notifier *notifier, void *data)
      */
     assert(!(info->secure_board_setup && kvm_enabled()));
 
+    info->dtb_filename = qemu_opt_get(qemu_get_machine_opts(), "dtb");
+
     /* Load the kernel.  */
     if (!info->kernel_filename || info->firmware_loaded) {
 
@@ -833,8 +835,6 @@ static void arm_load_kernel_notify(Notifier *notifier, void *data)
         elf_machine = EM_ARM;
     }
 
-    info->dtb_filename = qemu_opt_get(qemu_get_machine_opts(), "dtb");
-
     if (!info->secondary_cpu_reset_hook) {
         info->secondary_cpu_reset_hook = default_reset_secondary;
     }
diff --git a/vl.c b/vl.c
index c657acdd3c..2569ec24f8 100644
--- a/vl.c
+++ b/vl.c
@@ -4389,11 +4389,6 @@ int main(int argc, char **argv, char **envp)
         exit(1);
     }
 
-    if (!linux_boot && qemu_opt_get(machine_opts, "dtb")) {
-        error_report("-dtb only allowed with -kernel option");
-        exit(1);
-    }
-
     if (semihosting_enabled() && !semihosting_get_argc() && kernel_filename) {
         /* fall back to the -kernel/-append */
         semihosting_arg_fallback(kernel_filename, kernel_cmdline);