Re: [Qemu-devel] [PATCH] irq: introduce qemu_irq_proxy()

[Richard Henderson <rth@twiddle.net>]

On 09/18/2011 05:58 AM, Avi Kivity wrote:
> In some cases we have a circular dependency involving irqs - the irq
> controller depends on a bus, which in turn depends on the irq controller.
> Add qemu_irq_proxy() which acts as a passthrough, except that the target
> irq may be set later on.
> 
> Signed-off-by: Avi Kivity <avi@redhat.com>

Reviewed-by: Richard Henderson <rth@twiddle.net>

> ---
> 
> Turns out the circular dependency i8259->isa->pci->i8259 is widespread,
> so introduce a general means of fixing it up.  I'll update the patchset to
> make use of it everywhere it occurs.
> 
>  hw/irq.c |   14 ++++++++++++++
>  hw/irq.h |    5 +++++
>  2 files changed, 19 insertions(+), 0 deletions(-)
> 
> diff --git a/hw/irq.c b/hw/irq.c
> index 60eabe8..62f766e 100644
> --- a/hw/irq.c
> +++ b/hw/irq.c
> @@ -90,3 +90,17 @@ qemu_irq qemu_irq_split(qemu_irq irq1, qemu_irq irq2)
>      s[1] = irq2;
>      return qemu_allocate_irqs(qemu_splitirq, s, 1)[0];
>  }
> +
> +static void proxy_irq_handler(void *opaque, int n, int level)
> +{
> +    qemu_irq **target = opaque;
> +
> +    if (*target) {
> +        qemu_set_irq((*target)[n], level);
> +    }
> +}
> +
> +qemu_irq *qemu_irq_proxy(qemu_irq **target, int n)
> +{
> +    return qemu_allocate_irqs(proxy_irq_handler, target, n);
> +}
> diff --git a/hw/irq.h b/hw/irq.h
> index 389ed7a..64da2fd 100644
> --- a/hw/irq.h
> +++ b/hw/irq.h
> @@ -33,4 +33,9 @@ qemu_irq qemu_irq_invert(qemu_irq irq);
>  /* Returns a new IRQ which feeds into both the passed IRQs */
>  qemu_irq qemu_irq_split(qemu_irq irq1, qemu_irq irq2);
>  
> +/* Returns a new IRQ set which connects 1:1 to another IRQ set, which
> + * may be set later.
> + */
> +qemu_irq *qemu_irq_proxy(qemu_irq **target, int n);
> +
>  #endif