How to increase maxIntrCookies if default limit is reached in ESXi ?
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How to increase maxIntrCookies if default limit is reached in ESXi ?

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Article ID: 312151

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Updated On:

Products

VMware vSphere ESXi

Issue/Introduction

This article will provide a workaround to increase the number of interrupt cookies.

Symptoms:
1. Powering on a virtual machine with PCI Passthrough devices fails:                                                                              
•   In the vmware.log file of the affected virtual machine, you see entries similar to
    xxxx:xx:xx.x failed to register interrupt                                      
•   In the vmkernel.log file of the ESXi host where the virtual machine is running, you see
     entries similar to: 
     Unable to find a free interrupt number                    

2. Detection of devices fails while booting ESXi.

•   In the vmkernel.log file of the ESXi host, you see entries similar to: 
    Unable to find a free interrupt number


Environment

VMware vSphere ESXi 6.7
VMware vSphere ESXi 6.0
VMware vSphere ESXi 6.5
VMware vSphere ESXi 7.0.0

Cause

This issue occurs due to an ESXi limit on interrupt resources. When PCI Passthrough devices request many interrupts to be allocated, it is possible that this limit has been reached which causes the issue.

Resolution

VMware is aware of this issue and working to resolve this in a future release.

Workaround:
To work around this issue, adjust the boot option "maxIntrCookies" to increase the cookie limit.

Note: The maximum interrupt cookies is capped to 4096 even if you set it to a value that is > 4096.
For more information on instructions on how to configure boot options, see Configuring advanced options for ESXi/ESX (1038578 )

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