Re: [PATCH] x86: Don't allow nr_irqs > NR_IRQS

[Ben Hutchings <bhutchings@solarflare.com>]

On Tue, 2008-11-04 at 21:00 +0300, Cyrill Gorcunov wrote:
[...]
> | I hit this when running net-next-2.6 (close to 2.6.28-rc3) on a
> | Supermicro dual Xeon system.  NR_IRQS is 224 but probe_nr_irqs() detects
> | 5 IOAPICs (!) and returns 240.  Here are the log messages:
> | 
> | Tue Nov  4 16:53:47 2008 ACPI: IOAPIC (id[0x01] address[0xfec00000] gsi_base[0])
> | Tue Nov  4 16:53:47 2008 IOAPIC[0]: apic_id 1, version 32, address 0xfec00000, GSI 0-23
> | Tue Nov  4 16:53:47 2008 ACPI: IOAPIC (id[0x02] address[0xfec81000] gsi_base[24])
> | Tue Nov  4 16:53:47 2008 IOAPIC[1]: apic_id 2, version 32, address 0xfec81000, GSI 24-47
> | Tue Nov  4 16:53:47 2008 ACPI: IOAPIC (id[0x03] address[0xfec81400] gsi_base[48])
> | Tue Nov  4 16:53:47 2008 IOAPIC[2]: apic_id 3, version 32, address 0xfec81400, GSI 48-71
> | Tue Nov  4 16:53:47 2008 ACPI: IOAPIC (id[0x04] address[0xfec82000] gsi_base[72])
> | Tue Nov  4 16:53:47 2008 IOAPIC[3]: apic_id 4, version 32, address 0xfec82000, GSI 72-95
> | Tue Nov  4 16:53:47 2008 ACPI: IOAPIC (id[0x05] address[0xfec82400] gsi_base[96])
> | Tue Nov  4 16:53:47 2008 IOAPIC[4]: apic_id 5, version 32, address 0xfec82400, GSI 96-119
> | Tue Nov  4 16:53:47 2008 ACPI: INT_SRC_OVR (bus 0 bus_irq 0 global_irq 2 high edge)
> | Tue Nov  4 16:53:47 2008 ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 high level)
> | Tue Nov  4 16:53:47 2008 Enabling APIC mode:  Flat.  Using 5 I/O APICs
> | 
> | I think this has become possible since:
> | 
> | commit d6c88a507ef0b6afdb013cba4e7804ba7324d99a
> | Author: Thomas Gleixner <tglx@linutronix.de>
> | Date:   Wed Oct 15 15:27:23 2008 +0200
> | 
> |     genirq: revert dynarray
> | 
> |     Revert the dynarray changes. They need more thought and polishing.
> | 
> |     Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[...]
> Hi Ben,
> 
> I don't think that is because of Thomas' commit. If we've got
> number of pins larger then we expect it means something wrong
> with our NR_IRQS. Is it possible to get your .config?

Well there must have been an earlier change that resulted in detecting 5
IOAPICs instead of just 1, but that presumably would work as long as the
irq_desc array was dynamically allocated.  This reversion breaks that.

You don't really need to see the config; NR_IRQS is *always* 224 on
normal x86-32 systems.

Ben.

-- 
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.