How the Intel CPU connects to multiple IOAPICs and how it supports IOAPIC hotplug?

[haolee]

I can't find any material about how the Intel CPU connects multiple IOAPICs. Is this way possible? It's seems Linux kernel can support multiple IOAPICs and it even supports IOAPIC hotplug. But I can't find any documentation except some kernel patches from Intel developers. Is these information confidential?

[IntelSupport]

Hello haolee,

Thank you for posting in the Intel Community. 

I understand that you are looking for documentation about IOAPIC on the Intel® Xeon® processors.

• Can you provide us with more details about why are you looking for this documentation?
• Are you working on system development?
• What is the model of the intel processor that you are using on your system or that you are interested in?

Regards,

Leonardo C.

Intel Customer Support Technician

[haolee]

Hi, Leonardo,

Thanks for your reply.

Actually, I added Xeon tag to this post just because the forum system forced me to add a tag, so I selected a processor at random.

* I'm currently studying the Linux kernel interrupt mechanism. I'm familiar with x86 platform so I dived into IOAPIC related code. With the in-depth study, I found it's hard to understand some generic code unless I can know more details about multiple IOAPIC architecture. As far as I know, no virtual machine or emulator support adding a secondary IOAPIC, so the only way to learn multiple IOAPIC architecture is to find some documentations.

* Yes, I'm working on OS development and I may submit some patches to refine the IOAPIC related code

* To be honest, I don't know what processor should I be interested in. Any processor which support multiple IOAPICs should meet my needs.

Regards,
Hao Lee

[IntelSupport]

Hello haolee

Thank you for the details about the investigation that you are doing, allow me to look at it on my end.

I will be posting back as soon as is have any information

Regards,

Leonardo C.

Intel Customer Support Technician

[IntelSupport]

Hello haolee

Thank you for waiting.

After looking into your question the recommended support for it would be to contact our software developer site at https://software.intel.com/content/www/us/en/develop/home.html, in case you have issues to find information there to assist with your inquiry, please raise it in one of the Intel Software Forums (https://community.intel.com/t5/Software-Products/ct-p/software-products).

Regards,

Leonardo C.

Intel Customer Support Technician