Re: [Qemu-devel] [PATCH target-arm] arm: armv7m: Respect elf entry point

[Alistair Francis]

On Sat, Aug 2, 2014 at 9:41 AM, Peter Crosthwaite
<address@hidden> wrote:
> ARMv7M has it's own bootloader (separate from the regular ARM
> bootloader) that is elf aware. It is able to load elfs but it does
> not set the program counter to the elf entry point. Make it more
> consistent with the regular ARM bootloader by setting the program
> counter to the given elf entry point.
>
> Signed-off-by: Peter Crosthwaite <address@hidden>
> ---
>  hw/arm/armv7m.c | 19 ++++++++++++++++---
>  1 file changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/hw/arm/armv7m.c b/hw/arm/armv7m.c
> index 397e8df..d1b983f 100644
> --- a/hw/arm/armv7m.c
> +++ b/hw/arm/armv7m.c
> @@ -155,11 +155,18 @@ static void armv7m_bitband_init(void)
>
>  /* Board init.  */
>
> +typedef struct ARMV7MResetArgs {
> +    ARMCPU *cpu;
> +    uint32_t reset_pc;
> +} ARMV7MResetArgs;
> +
>  static void armv7m_reset(void *opaque)
>  {
> -    ARMCPU *cpu = opaque;
> +    ARMV7MResetArgs *args = opaque;
>
> -    cpu_reset(CPU(cpu));
> +    cpu_reset(CPU(args->cpu));
> +    args->cpu->env.regs[15] = args->reset_pc;
> +    args->cpu->env.thumb = args->reset_pc & 1;
>  }

This breaks a simple test case that I have. It now starts at a an
address one one bit larger but causes the program to hang.
If the 'cpu_reset(CPU(args->cpu))' is moved to the end of the function
the test boots (the same as it did before).

>
>  /* Init CPU and memory for a v7-M based board.
> @@ -183,6 +190,7 @@ qemu_irq *armv7m_init(MemoryRegion *address_space_mem,
>      MemoryRegion *sram = g_new(MemoryRegion, 1);
>      MemoryRegion *flash = g_new(MemoryRegion, 1);
>      MemoryRegion *hack = g_new(MemoryRegion, 1);
> +    ARMV7MResetArgs reset_args;
>
>      flash_size *= 1024;
>      sram_size *= 1024;
> @@ -259,7 +267,12 @@ qemu_irq *armv7m_init(MemoryRegion *address_space_mem,
>      vmstate_register_ram_global(hack);
>      memory_region_add_subregion(address_space_mem, 0xfffff000, hack);
>
> -    qemu_register_reset(armv7m_reset, cpu);
> +    reset_args = (ARMV7MResetArgs) {
> +        .cpu = cpu,
> +        .reset_pc = entry,
> +    };
> +    qemu_register_reset(armv7m_reset,
> +                        g_memdup(&reset_args, sizeof(reset_args)));
>      return pic;
>  }
>
> --
> 1.9.1
>