Re: [PATCH 11/12 gnumach] smp: Serialise AP bringup

[Samuel Thibault]

Damien Zammit, le mar. 31 janv. 2023 09:39:35 +0000, a ecrit:
> @@ -262,11 +259,14 @@ cpu_setup()
>  void
>  cpu_ap_main()
>  {
> +    unsigned apic_id = (((ApicLocalUnit*)phystokv(lapic_addr))->apic_id.r >> 
> 24) & 0xff;
> +    int cpu = apic_get_cpu_kernel_id(apic_id);
> +
>      do {
>          asm volatile ("pause" : : : "memory");

I believe you actually want a full __sync_synchronize() barrier,
otherwise the booted AP may not be getting all variables flushes from
the BSP.

> @@ -309,16 +309,12 @@ start_other_cpus(void)
>               //Start cpu
>               printf("Starting AP %d\n", cpu);
>               cpu_start(cpu);
> -     }
> -     printf("BSP: Completed SMP init\n");
> -     bspdone = 1;
> 
> -     for (cpu = 1; cpu < ncpus; cpu++) {
> +             bspdone++;
>               do {
>                       asm volatile ("pause" : : : "memory");

And conversely here, I believe you actually want a full __sync_synchronize() 
barrier,
otherwise the BSP may not be getting all variables flushes from
the booted AP.

>               } while (machine_slot[cpu].running == FALSE);
>       }
> -
> -        cpu_intr_restore(flags);
> +     printf("BSP: Completed SMP init\n");
>  }
>  #endif       /* NCPUS > 1 */

> diff --git a/i386/intel/pmap.c b/i386/intel/pmap.c
> index 5cd68878..754334c9 100644
> --- a/i386/intel/pmap.c
> +++ b/i386/intel/pmap.c
> @@ -2920,6 +2920,7 @@ void pmap_update_interrupt(void)
>       int             s;
> 
>       my_cpu = cpu_number();
> +     printf("PMAP(%d)\n", my_cpu);
> 
>       /*
>        *      Exit now if we're idle.  We'll pick up the update request

Avoid leftovers :)

Samuel