Re: [PATCH ARM v8 1/4] mini-os: arm: time

[Ian Campbell <Ian.Campbell@citrix.com>]

On Fri, 2014-10-03 at 10:20 +0100, Thomas Leonard wrote:
> Based on an initial patch by Karim Raslan.
> 
> Signed-off-by: Karim Allah Ahmed <karim.allah.ahmed@gmail.com>
> Signed-off-by: Thomas Leonard <talex5@gmail.com>

Acked-by: Ian Campbell <ian.campbell@citrix.com>

> +/* Wall-clock time is not currently available on ARM, so this is always zero for now:
> + * http://wiki.xenproject.org/wiki/Xen_ARM_TODO#Expose_Wallclock_time_to_guests

I have some slightly hacky patches for this, I really should dust them
off and submit them...

> +void block_domain(s_time_t until)
> +{
> +    uint64_t until_count = ns_to_ticks(until) + cntvct_at_init;
> +    ASSERT(irqs_disabled());
> +    if (read_virtual_count() < until_count)
> +    {
> +        set_vtimer_compare(until_count);
> +        __asm__ __volatile__("wfi");
> +        unset_vtimer_compare();
> +
> +        /* Give the IRQ handler a chance to handle whatever woke us up. */
> +        local_irq_enable();
> +        local_irq_disable();
> +    }

Just wondering, is this not roughly equivalent to a wfi loop with
interrupts enabled?