Re: 2.6.19-rc1 genirq causes either boot hang or "do_IRQ: cannot handle IRQ -1"

[ebiederm@xmission.com (Eric W. Biederman)]

Muli Ben-Yehuda <muli@il.ibm.com> writes:

> On Fri, Oct 06, 2006 at 05:42:40PM -0600, Eric W. Biederman wrote:
>
>> If I read your bootlog right. You have logical cpus, but only two
>> sockets, and I think only two cores.  The other two logical cpus
>> being hyperthreaded.
>
> Yes, 2 sockets each of which is HT. Here's a /proc/cpuinfo from a
> distro kernel:

Ok.  From looking at an individual case the ioapic is programmed
correctly and I don't see a reason the local apic would be programmed
incorrectly.  However logical delivery mode and lowest priority
delivery mode are enabled.  So we are asking the interrupt delivery
subsystem to choose a cpu to deliver the interrupt to and then are not
giving the cpu any choice.  So we may be confusing things. 

Can you try CONFIG_CPU_HOTPLUG?  That will force genapic to be set
to genapic_physflat instead of genapic_flat.

I am hoping that by running the apics in a different delivery mode
that explicitly says just deliver this interrupt to this cpu we
will avoid the problem you are seeing.

If genapic_physflat works we will have to decide what to do about
genapic_flat.

Thanks,

Eric