Re: [PATCH] x86: fix probe_nr_irqs for xen

["Yinghai Lu" <yhlu.kernel@gmail.com>]

On Thu, Aug 21, 2008 at 4:52 PM, Jeremy Fitzhardinge <jeremy@goop.org> wrote:
> Yinghai Lu wrote:
>> On Thu, Aug 21, 2008 at 4:33 PM, Jeremy Fitzhardinge <jeremy@goop.org> wrote:
>>
>>> Yinghai Lu wrote:
>>>
>>>> otherwise Xen is _completely_ unusable with 5 or more VCPUs.
>>>> ( when !CONFIG_HAVE_SPARSE_IRQ)
>>>>
>>>> based on Alex's patch
>>>>
>>>> also add +1 offset after redir_entries
>>>>
>>>> Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
>>>> Cc: Alex Nixon <alex.nixon@citrix.com>
>>>>
>>>>
>>> Looks good to me.  We can fix this in a better way later.
>>>
>>
>> later could set CONFIG_HAVE_SPARSE_IRQ to true by default.
>>
>
> Well, perhaps.  But we can use vectors rather than IRQs for Xen event
> channel mappings, which will save us from having to allocate lots of
> per-cpu irqs.

like system vectors with smp-ipi etc?

>
> Also, implementing probe_nr_irqs() in a more generic (rather than
> io_apic-specific) way.  Using some interface that queries each irq chip
> for how many irqs it supports, or something.

hope we can kill nr_irqs/NR_IRQS

YH