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Message-ID: <86802c440808191124v39ce2aa9rb548d3bdd75ca25c@mail.gmail.com>
Date: Tue, 19 Aug 2008 11:24:53 -0700
From: "Yinghai Lu" <yhlu.kernel@gmail.com>
To: "Alex Nixon (Intern)" <Alex.Nixon@citrix.com>
Subject: Re: [PATCH] X86: Change the default value of nr_irqs from 32 to NR_IRQs
Cc: "Ingo Molnar" <mingo@elte.hu>,
       "Jeremy Fitzhardinge" <Jeremy.Fitzhardinge@citrix.com>,
       "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
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On Tue, Aug 19, 2008 at 11:13 AM, Alex Nixon (Intern)
<Alex.Nixon@citrix.com> wrote:
> Yinghai Lu <yhlu.kernel@gmail.com> wrote:
>>On Tue, Aug 19, 2008 at 9:55 AM, Alex Nixon <alex.nixon@citrix.com> wrote:
>>>
>>> If the number of discovered IRQs is suspiciously low, this patch causes
>>> the number reported to default to NR_IRQS, rather than 32.  NR_IRQS has
>>> already been defined to be a >sensible value for the current system (in
>>> particular, at least 224 when paravirtualisation is involved).
>>>
>>if only one ioapic, nr will be 24<<1, you will get 48. Does pv has io apic
>> ?
>>
>>YH
>>
> I'm not sure about the general case, but Xen does not (Jeremy correct me if
> I'm wrong).
>
> Unless I'm missing something (which I may well be; I'm new to this area of
> code), it seems more logical anyway to default back to the calculated
> system-specific value (NR_IRQS), instead of 32, which seems rather
> arbitrary.

can you try !CONFIG_HAVE_SPARSE_IRQ and CONFIG_HAVE_SPARSE_IRQ ?

YH
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