Re: [PATCH 1/2] target/hppa: Add CPU reset method

[Philippe Mathieu-Daudé]

On 30/12/24 00:41, deller@kernel.org wrote:
> From: Helge Deller <deller@gmx.de>
>
> Add the CPU reset method, which resets all CPU registers and the TLB to
> zero. Then the CPU will switch to 32-bit mode (PSW_W bit is not set) and
> start execution at address 0xf0000004.
> Although we currently want to zero out all values in the CPUHPPAState
> struct, add the end_reset_fields marker in case the state structs gets
> extended with other variables later on which should not be reset.
>
> Signed-off-by: Helge Deller <deller@gmx.de>
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
>
> V4:
> - Drop initialization of exception_index in hppa_cpu_initfn()
>
> V3:
> - Call reset function from hppa_machine_reset() instead
>
> V2:
> - Add end_reset_fields marker
> - call reset function in hppa_cpu_initfn()
> ---
>   hw/hppa/machine.c |  6 +++---
>   target/hppa/cpu.c | 26 ++++++++++++++++++++++++--
>   target/hppa/cpu.h |  5 +++++
>   3 files changed, 32 insertions(+), 5 deletions(-)


> +static void hppa_cpu_reset_hold(Object *obj, ResetType type)
> +{
> +    HPPACPU *cpu = HPPA_CPU(obj);
> +    HPPACPUClass *scc = HPPA_CPU_GET_CLASS(cpu);
> +    CPUHPPAState *env = &cpu->env;
> +    CPUState *cs = CPU(cpu);
> +
> +    if (scc->parent_phases.hold) {
> +        scc->parent_phases.hold(obj, type);

This ends calling cpu_common_reset_hold() ...

> +    }
> +
> +    memset(env, 0, offsetof(CPUHPPAState, end_reset_fields));
> +    cpu_set_pc(cs, 0xf0000004);
> +    cpu_hppa_put_psw(env, hppa_is_pa20(env) ? PSW_W : 0);
> +    cpu_hppa_loaded_fr0(env);
> +
> +    cs->exception_index = -1;
> +    cs->halted = 0;

... which already sets these values. Why is that required?

> +}