Re: [PATCH] X86: Change the default value of nr_irqs from 32 to NR_IRQs
From: Alex Nixon
Date: Tue Aug 19 2008 - 15:51:16 EST
Yinghai Lu wrote:
On Tue, Aug 19, 2008 at 11:32 AM, Alex Nixon <alex.nixon@xxxxxxxxxx> wrote:
Yinghai Lu wrote:
On Tue, Aug 19, 2008 at 11:13 AM, Alex Nixon (Intern)
<Alex.Nixon@xxxxxxxxxx> wrote:
Yinghai Lu <yhlu.kernel@xxxxxxxxx> wrote:
On Tue, Aug 19, 2008 at 9:55 AM, Alex Nixon <alex.nixon@xxxxxxxxxx>
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
Sorry I should have mentioned originally - the bug occurs both with
CONFIG_HAVE_SPARSE_IRQ enabled, and disabled.
maybe we need special probe_nr_irqs for PV or not call that in
setup_arch for xen -- it will leave nr_irqs == NR_IRQS
YH
That would be one solution, but would be more involved than this trivial
patch (although if considered more 'correct' then it is of course worth
the effort).
But attempting to keep things simple, is there a reason it's
preferable to fall back to 32 rather NR_IRQS?
- Alex
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/