RE: [Xen-devel] Maximum number of domains and NR_IRQS

["Carb, Brian A" <Brian.Carb@xxxxxxxxxx>]

Keir,

 

We changed NR_IRQS in xen-unstable.hg/linux-2.6.16.33-xen/include/asm-x86_64/irq.h - it's set to 224 by default.

brian carb
unisys corporation - malvern, pa
brian.carb@xxxxxxxxxx

 

---

From: Keir Fraser [mailto:keir@xxxxxxxxxxxxx]
Sent: Thursday, December 07, 2006 10:51 AM
To: Carb, Brian A; xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] Maximum number of domains and NR_IRQS

On 7/12/06 15:37, "Carb, Brian A" 
<Brian.Carb@xxxxxxxxxx> wrote:

> We successfully start 118 
>   DOMUs, but when we try to start the 119th, the system panics with the 
>   following messages:
>   Kernel panic - not syncing: No available 
>   IRQ to bind to: increase NR_IRQS!
>   (XEN) Domain 0 crashed: 
>   rebooting machine in 5 seconds.
>
> The documentation in 
>   include/asm-x86_64/irq.h suggests that the value of NR_IRQS under x86_64 is 
>   limited to 256. In fact, when we rebuilt xen-unstable with NR_IRQS set to 768, 
>   the kernel panics on boot (see below).

It’s not 
Xen’s NR_IRQS you should increase; only Linux’s.

This out-of-IRQs 
condition shouldn’t crash the dom0 of course. I’ll look into 
that.

 -- Keir
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