Requirements to use a large Memory Mapped I/O PCI BARs on vSphere
Article ID: 345189
Updated On:
Products
VMware vSphere ESXi
Issue/Introduction
This article provides about the requirement to use PCI devices with large MMIO PCI BARs (Base Address Registers) on vSphere hosts.
Environment
VMware vSphere ESXi 6.0
Resolution
vSphere 6.0 supports some PCI devices with large (64-bit) Base Address Registers (BARs) and/or MMIO regions larger than 1 GB.
To use VM DirectPath I/O (Passthrough) with large BAR PCI devices, you have to edit the .vmx file of a virtual machine attached to the device. For more information on editing .vmx file, see Tips for editing a .vmx file (1714).
Note: Before you edit the .vmx file, take a backup copy of the .vmx file.
- For PCI devices with MMIO regions larger than 1GB, use this flag in the .vmx file to set the firmware mode to EFI:
firmware="efi"
Note: Setting a virtual machine's firmware mode to EFI requires re-installation of the guest operating system. Do not change the firmware mode of the virtual machine with a guest operating system already installed.
- For PCI devices with 64-bit BARs, ensure this flag is set in the .vmx file:
pciPassthru.use64bitMMIO="TRUE"
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