Re: [Qemu-devel] [RESEND PATCH v9 2/4] x86: use new method to correct reset sequence

[Eduardo Habkost]

On Wed, Aug 19, 2015 at 05:36:30PM +0800, Zhu Guihua wrote:
> Something must be occur during reset of the X86 platform in a specific
> order. For example, the apic reset should be after some devices (such
> as hpet, rtc) reset, so that the apic register could be set to default
> values.

Can you explain in the commit message (and in a comment below) why
exactly the apic register won't be set to default values if it isn't
reset after all other devices?

> 
> This patch uses the new QEMUMachine reset method to solve the above
> problem, ensuring the various reset happen in the correct order.
> 
> Signed-off-by: Zhu Guihua <address@hidden>
> ---
>  hw/i386/pc.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 8b7dbe5..0e83dc9 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1929,6 +1929,22 @@ static void pc_machine_initfn(Object *obj)
>                               NULL, &error_abort);
>  }
>  
> +static void pc_machine_reset(void)
> +{
> +    CPUState *cs;
> +    X86CPU *cpu;
> +
> +    qemu_devices_reset();
> +

Please add a comment to the function explaining why this ordering is
important.

> +    CPU_FOREACH(cs) {
> +        cpu = X86_CPU(cs);
> +
> +        if (cpu->apic_state) {
> +            device_reset(cpu->apic_state);
> +        }
> +    }
> +}
> +
>  static unsigned pc_cpu_index_to_socket_id(unsigned cpu_index)
>  {
>      unsigned pkg_id, core_id, smt_id;
> @@ -1949,6 +1965,7 @@ static void pc_machine_class_init(ObjectClass *oc, void 
> *data)
>      mc->default_boot_order = "cad";
>      mc->hot_add_cpu = pc_hot_add_cpu;
>      mc->max_cpus = 255;
> +    mc->reset = pc_machine_reset;
>      hc->plug = pc_machine_device_plug_cb;
>      hc->unplug_request = pc_machine_device_unplug_request_cb;
>      hc->unplug = pc_machine_device_unplug_cb;
> -- 
> 1.9.3
> 

-- 
Eduardo