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Date: Sat, 15 Oct 2016 14:14:01 +0100
From: Marc Zyngier <marc.zyngier@arm.com>
To: Bharat Kumar Gogada <bharat.kumar.gogada@xilinx.com>
Cc: "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Bjorn Helgaas <helgaas@kernel.org>, "arnd@arndb.de" <arnd@arndb.de>
Subject: Re: Why MSI is limited to 32 interrupts maximum
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On Sat, 15 Oct 2016 12:37:55 +0000
Bharat Kumar Gogada <bharat.kumar.gogada@xilinx.com> wrote:

Hi Bharat,

> Can anyone tell why MSI interrupts are limited to maximum 32
> interrupts, even though we have 16bit message data register ?

That's the very definition of the original PCI MSI: Up to 32
consecutive interrupts per function, and a single doorbell address.
MSI-X lifts that restriction and offers up to 2048 interrupts that do
not have to be contiguous can target individual doorbells. Assuming
your MSI controller advertises MSI-X support and that your devices do
support it as well, you'll be able to enjoy those.

> 
> Regards,
> Bharat
> 
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	M.
-- 
Without deviation from the norm, progress is not possible.