Re: [Qemu-devel] [PATCH] Make -kernel flag optional on ARM.

[Peter Maydell]

On 10 July 2013 08:33, Grant Likely <address@hidden> wrote:
> Sometimes we want to boot the system via firmware instead of loading a
> kernel into ram with the -kernel parameter. This patch makes the -kernel
> parameter optional so that a bios image provided by the -pflash flag
> will be executed.
>
> For example:
> qemu-system-arm -M vexpress-a15 -pflash <filename>
>
> Note: Currently the file must be at least the size of the emulated flash
> device (64M) otherwise QEMU will silently not use the data. This will be
> fixed in a separate patch
>
> This is part of the larger solution. For this to work it requires the
> platform to have flash mapped or aliased to address 0 so that there is
> some code for the emulator to execute.

That patch is already on list :-)

> Signed-off-by: Grant Likely <address@hidden>
> Cc: Peter Maydell <address@hidden>
> Cc: address@hidden
> ---
>
>  hw/arm/boot.c | 47 ++++++++++++++++++++++-------------------------
>  1 file changed, 22 insertions(+), 25 deletions(-)
>
> diff --git a/hw/arm/boot.c b/hw/arm/boot.c
> index 7c0090f..3b9e108 100644
> --- a/hw/arm/boot.c
> +++ b/hw/arm/boot.c
> @@ -361,12 +361,6 @@ void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info 
> *info)
>      int big_endian;
>      QemuOpts *machine_opts;
>
> -    /* Load the kernel.  */
> -    if (!info->kernel_filename) {
> -        fprintf(stderr, "Kernel image must be specified\n");
> -        exit(1);
> -    }

Why can't we just return from the function here? If we don't
have a kernel we can assume we don't have a dtb or an initrd
either. I don't think we want to do any of the other weird
stuff with setting up a reset handler or boot pen for the
secondary CPUs either -- we should just assume the bootrom
image in the flash handles this.

thanks
-- PMM