Did PCI/IRQ allocation change significantly after 4.2 kernel?

[greg@kroah.com (Greg KH)]

On Wed, Mar 30, 2016 at 05:24:40PM -0400, Rob Groner wrote:
> And, we have a winner!
> 
> -----------------------------------------------------------------------
> rtd at kernel-dev:~/git/kernels/linux$ git bisect good
> 991de2e59090e55c65a7f59a049142e3c480f7bd is the first bad commit
> commit 991de2e59090e55c65a7f59a049142e3c480f7bd
> Author: Jiang Liu <jiang.liu@linux.intel.com>
> Date:   Wed Jun 10 16:54:59 2015 +0800
> 
>     PCI, x86: Implement pcibios_alloc_irq() and pcibios_free_irq()
>     
>     To support IOAPIC hotplug, we need to allocate PCI IRQ resources on
> demand
>     and free them when not used anymore.
>     
>     Implement pcibios_alloc_irq() and pcibios_free_irq() to dynamically
>     allocate and free PCI IRQs.
>     
>     Remove mp_should_keep_irq(), which is no longer used.
>     
>     [bhelgaas: changelog]
>     Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
>     Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
>     Acked-by: Thomas Gleixner <tglx@linutronix.de>
> 
> :040000 040000 765e2d5232d53247ec260b34b51589c3bccb36ae
> f680234a27685e94b1a35ae2a7218f8eafa9071a M	arch
> :040000 040000 d55a682bcde72682e883365e88ad1df6186fd54d
> f82c470a04a6845fcf5e0aa934512c75628f798d M	drivers
> ----------------------------------------------------------------
> 
> I'll sort out what all of that means tomorrow...

Great job, please email these developers, and the pci mailing list with
the information and they will help you out.

greg k-h