Re: [Qemu-devel] [Patch v4 6/8] target_arm: Change the reset values based on the ELF entry

[Martin Galvan <martin.galvan@tallertechnologies.com>]

On Tue, Oct 7, 2014 at 11:13 AM, Alistair Francis <alistair23@gmail.com> wrote:
> The Netduino 2 machine won't run unless the reset_pc is based
> on the ELF entry point.
>
> Signed-off-by: Alistair Francis <alistair23@gmail.com>
> Signed-off-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
> ---
> V2:
>  - Malloc straight away, thanks to Peter C
>
>  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 7169027..07b36e2 100644
> --- a/hw/arm/armv7m.c
> +++ b/hw/arm/armv7m.c
> @@ -155,11 +155,19 @@ 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(args->cpu));
>
> -    cpu_reset(CPU(cpu));
> +    args->cpu->env.thumb = args->reset_pc & 1;
> +    args->cpu->env.regs[15] = args->reset_pc & ~1;
>  }
>
>  /* Init CPU and memory for a v7-M based board.
> @@ -180,6 +188,7 @@ qemu_irq *armv7m_init(MemoryRegion *system_memory, int mem_size, int num_irq,
>      int i;
>      int big_endian;
>      MemoryRegion *hack = g_new(MemoryRegion, 1);
> +    ARMV7MResetArgs *reset_args = g_new0(ARMV7MResetArgs, 1);
>
>      if (cpu_model == NULL) {
>         cpu_model = "cortex-m3";
> @@ -234,7 +243,11 @@ qemu_irq *armv7m_init(MemoryRegion *system_memory, int mem_size, int num_irq,
>      vmstate_register_ram_global(hack);
>      memory_region_add_subregion(system_memory, 0xfffff000, hack);
>
> -    qemu_register_reset(armv7m_reset, cpu);
> +    *reset_args = (ARMV7MResetArgs) {
> +        .cpu = cpu,
> +        .reset_pc = entry,
> +    };
> +    qemu_register_reset(armv7m_reset, reset_args);
>      return pic;
>  }

How does this differ from what's being done in arm_cpu_reset for
ARMv7-M? What about the initial MSP?

-- 

Martín Galván

Software Engineer

Taller Technologies Argentina


San Lorenzo 47, 3rd Floor, Office 5

Córdoba, Argentina

Phone: 54 351 4217888 / +54 351 4218211