PCI Endpoint Function Drivers (test, NTB, vNTB, Qualcomm MHI)
A small set of helpers that let a Linux system act as a PCI Express endpoint (the device side of a PCIe link) rather than the usual host side. They cover loopback test gadgets, non-transparent bridging between two hosts, virtual NTB, and Qualcomm's MHI endpoint mode used on SoCs like SA8775P, SDX55, and SM8450 in automotive and modem deployments.
recommendation
It should stay because the PCI endpoint framework is current, documented kernel infrastructure with no replacement, and the Qualcomm MHI endpoint piece in particular is actively maintained — a stable backport adding SA8775P device IDs landed in 2025, and hardware like NXP S32G3 automotive processors and Lantronix SA8775P-based platforms are still being sold for new designs. Volume is modest, but the subsystem is clearly alive and serving shipping silicon.
repository signals
sources
- docs.kernel.org
Kernel documentation treats PCI endpoint functions as a current supported framework area, with dedicated sections for test, NTB, and vNTB endpoint functions.
- docs.kernel.org
vNTB is documented as an active endpoint-function use case, not a legacy-only leftover.
- docs.kernel.org
The NTB endpoint function has current configfs binding documentation, indicating ongoing supported deployment.
- cateee.net
LKDDb shows CONFIG_PCI_EPF_MHI present in current kernel series and lists active Qualcomm endpoint IDs including SA8775P, SDX55, and SM8450.
- spinics.net
A 2025 stable backport updated SA8775P device ID support in pci-epf-mhi, showing recent upstream maintenance rather than retirement.
- nxp.com
NXP still markets S32G3 automotive processors as active products with PCIe-capable automotive deployments relevant to EP/NTB-style endpoint use cases.
- lantronix.com
SA8775P-based development hardware is marketed as new/current, supporting the case that Qualcomm endpoint-function hardware is still entering new deployments.
codex reasoning notes (technical)
Local shell inspection showed four loadable EPF drivers in this directory (`pci-epf-test`, `pci-epf-ntb`, `pci-epf-vntb`, `pci-epf-mhi`) and Kconfig describes active PCI endpoint test/NTB/MHI roles. URLs were obtained via `web.search_query`; no removal/deprecation discussions surfaced in lore-targeted searches. docs.kernel URLs show this directory maps to currently documented endpoint-function features; LKDDb and the 2025 stable patch URL show active kernel support for modern Qualcomm MHI endpoint parts; NXP/Lantronix product pages indicate relevant endpoint-capable automotive hardware is still sold for new designs. This is a niche subsystem, so deployments are not high-volume, but it is clearly maintained and still relevant; no natural replacement driver covers the whole directory.