Windows 10 Insider Program IRQ Issue

Hi JG,

This could be a hardware-related concern. But for us to dig deeper on this issue, we would like to ask for the following information:

• What IRQs did you receive?
• Were there any changes or updates performed on your computer prior to the issue?
• Does the IRQ appear for a particular device?

If possible, please send us a screenshot of the IRQs that you receive so we can look into it. You may also look into this link and see if this helps.

Looking forward to your reply.

Regards.

Hi,

As per my post, multiple IRQ's have been set for 'Microsoft ACPI-compliant System'. The number range allocated is 54-511! This appears hardware independent as the same issue is on my laptop and two desktop PC's. Also, the 'device' / IRQ can't be uninstalled.

The only updates are upgrades to the latest Insider Preview build of Windows 10 (16193). But, the problem may have been around for some time. I believe this is a Windows 10 issue as its the same on all three machines.

Regards

Thanks for the feedback, JG. Could you provide us a screenshot of the IRQs that you received so we can further check on it? We'd like to make sure that we properly identify why you're receiving these interruptions.

Looking forward to your reply.

Regards.

Hi,

Here are the screenshots as requested:

Hope you find these helpful.

Regards

John Griffiths

What sort of issues are you experiencing ? 

I have the same IRQs and they aren't causing any problems in my system.

This is how Windows deals with hardware and should be transparent to you.

I can only see these IRQs when I look into msinfo32 utility \Hardware Resources\IRQs.

But yours appear in Device Manager. Right. I don't see them in my Device Manager.

Still, do you experience any slow-downs, crashes, etc. ?

Hope this helps.

Hi,

I found the 'excess' IRQ's initially on one machine when trying to resolve a conflict. The system will not let me re-assign the IRQ's. My perception is that servicing / poling the IRQ's will lead to a slowdown in the system.

My original question is why so many and I assumed a W10 fault for generating so many. Shooting up from under 20 to over five hundred IRQ's seems strange as there aren't an more devices. Also, you will see the IRQ numbers go negative, which can't be good can it?

Regards

John Griffiths

As I said in my previous post, there is nothing wrong with the number of IRQs in your system. There is an equal number of IRQs in my system, too. And some of them have a negative sign as you can see from the below screenshot.

MSinfo32 has these IRQs in Hardware resources section:

The only thing is that I do not see these IRQs in my Device Manager.

If there is no problem with the devices, which means you have an OK sign besides them, there should be nothing to worry about.

Hope this helps.

I have the same IRQ list and although I have no problems it would be nice to know what it's ment to be. All the MS ACPI entry's appear to be one device that has claimed a load of imposible (ISA!) IRQ's. You just can't have more than 256 interrupts as they won't fit in the IDT.

Looks like it may have something to do with message signaled interrupts working in proper MSI-X/x2APIC mode. Going to look into it.

Well I looked into it but I wish I hadn't because now my head hurts !

I used the kernel debugger to look at the Interrupt descriptor table with the ! idt command but there is nothing much in it. The first 32 entries are the expected CPU exception handlers and there are a few entries for non PCI devices like my PS/2 keyboard and such but the stand out one is for ACPI.

My system is indeed using message signalled interrupts for all PCI/PCIe devices as my local APIC is in x2APIC mode (I used the ! apic command to check) so that left me looking at MSI's.

PCI devices that are capable of MSI's signal interupts by writing to a reserved memory address (I assume its the IOAPIC I/O control register) with a vector number they were asigned by windows at system start up. Thats all well and good because the vector is an 8 bit number and it ties up with the 256 entries in the IDT. The trouble is that's NOT how it works because then the IDT would have all my devices listed.

Further reading told me that with MSI-X each device can write to upto 2048 different memory addresses to signal different interrupts and that the x2APIC puts its registers in a totally different address space reserved for machine specific registers.

At that point I gave up.

All I can say is that at every system start up the Windows plug and play manager uses the ACPI driver to progam PCI devices. Devices then send messages with enough infomation to allow the interrupt dispatcher to find the correct interrupt object.

I still don't know what the entries in device manager mean but i'm not going to worry any more !