Re: Why MSI is limited to 32 interrupts maximum
From: Marc Zyngier
Date: Sat Oct 15 2016 - 09:14:21 EST
On Sat, 15 Oct 2016 12:37:55 +0000
Bharat Kumar Gogada <bharat.kumar.gogada@xxxxxxxxxx> wrote:
> 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.
> This email and any attachments are intended for the sole use of the
> named recipient(s) and contain(s) confidential information that may
> be proprietary, privileged or copyrighted under applicable law. If
> you are not the intended recipient, do not read, copy, or forward
> this email message or any attachments. Delete this email message and
> any attachments immediately.
Please fix your email not to carry such disclaimer (or use a private
email address if you can't work around your company policy). Posting
confidential information on a public mailing list feels a bit silly.
Without deviation from the norm, progress is not possible.