Setting up the PCIe support

Red Hat Enterprise Linux 8.6 LPAR mode z/VM guest KVM guest

Configure the PCIe support through the pci= kernel parameter.

PCIe devices are automatically configured during the system boot process. In contrast to most IBM Z® devices, all PCIe devices that are in a configured state are automatically set online. PCIe devices that are in stand-by state are not automatically enabled.

Scanning of PCIe devices is enabled by default. To disable use of PCI devices, set the kernel command line parameter pci=off.

Figure 1. PCI kernel parameter syntax

where:

Draft comment: MariaEisenhaendler
KRN1804 (force_floating) still deferred.

off: disables automatic scanning of PCIe devices.
on: enables automatic scanning of PCIe devices (default).

pci=nomio: if available, PCIe uses enhanced instructions as introduced with z15®. Specify this kernel parameter to use the previous instructions.
pci=norid: PCI function addresses follow an Alternative Routing-ID Interpretation (ARI) conform format if it is supported by the system environment. Specify this kernel parameter to use the previous format.

Attention: Other PCI kernel parameters do not apply to IBM Z and might have adverse effects on your system.

Example

The following kernel parameter enables automatic scanning of PCIe devices.

pci=on