Re: [Minios-devel] [UNIKRAFT PATCHv5 24/46] plat/kvm: Introduce a time_ops for different architectures

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

Hi Wei,

On 10.08.2018 09:08, Wei Chen wrote:
> Different architectures have different timer implementation. In
> order to avoid using too many #ifdef, we introduce this time_ops
> for different architectures to implement arch_timer_ops.
does the timer implementation this change during runtime or can you 
settle on one specific timer implementation during compile time?
Why not providing a different C file that implements your ARM timer? We 
could avoid the indirection and save the timeops struct.
> Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
> ---
>   include/uk/plat/time.h | 8 ++++++++
>   plat/kvm/time.c        | 7 ++++---
>   plat/kvm/tscclock.c    | 6 ++++++
>   3 files changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/include/uk/plat/time.h b/include/uk/plat/time.h
> index 202e0f9..2aacfce 100644
> --- a/include/uk/plat/time.h
> +++ b/include/uk/plat/time.h
> @@ -47,6 +47,14 @@ void ukplat_time_fini(void);
>   
>   __nsec ukplat_monotonic_clock(void);
>   
> +struct ukplat_time_ops {
> +       int (*init)(void);
> +       __u64 (*monotonic)(void);
> +       __u64 (*epochoffset)(void);
> +};
> +
> +extern struct ukplat_time_ops arch_timer_ops;
> +
>   #ifdef __cplusplus
>   }
>   #endif
> diff --git a/plat/kvm/time.c b/plat/kvm/time.c
> index 1fb48bf..eb8bfc2 100644
> --- a/plat/kvm/time.c
> +++ b/plat/kvm/time.c
> @@ -31,17 +31,18 @@
>   #include <kvm/tscclock.h>
>   #include <uk/assert.h>
>   
> +struct ukplat_time_ops *time_ops = &arch_timer_ops;
>   
>   /* return ns since time_init() */
>   __nsec ukplat_monotonic_clock(void)
>   {
> -       return tscclock_monotonic();
> +       return time_ops->monotonic();
>   }
>   
>   /* return wall time in nsecs */
>   __nsec ukplat_clock_wall(void)
>   {
> -       return tscclock_monotonic() + tscclock_epochoffset();
> +       return time_ops->monotonic() + time_ops->epochoffset();
>   }
>   
>   static int timer_handler(void *arg __unused)
> @@ -59,7 +60,7 @@ void ukplat_time_init(void)
>         if (rc < 0)
>                 UK_CRASH("Failed to register timer interrupt handler\n");
>   
> -	rc = tscclock_init();
> +       rc = time_ops->init();
>         if (rc < 0)
>                 UK_CRASH("Failed to initialize TSCCLOCK\n");
>   }
> diff --git a/plat/kvm/tscclock.c b/plat/kvm/tscclock.c
> index 8961659..990902b 100644
> --- a/plat/kvm/tscclock.c
> +++ b/plat/kvm/tscclock.c
> @@ -358,3 +358,9 @@ void time_block_until(__snsec until)
>                         break;
>         }
>   }
> +
> +struct ukplat_time_ops arch_timer_ops = {
> +       .init = tscclock_init,
> +       .monotonic = tscclock_monotonic,
> +       .epochoffset = tscclock_epochoffset,
> +};
Thanks,

Simon

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