RISC-V ACPI platform support
Glue code that lets Linux boot and configure RISC-V systems whose firmware describes the hardware using ACPI tables (the same mechanism PCs and ARM servers use) rather than devicetree. It targets emerging RISC-V server and workstation platforms standardized under UEFI/ACPI 6.5 and later, including CPU performance scaling via CPPC and IOMMU topology via the new RIMT table.
recommendation
It should stay because RISC-V ACPI is an actively developed boot and platform-description path for modern RISC-V systems, with new work landing in 2025-2026 around CPPC power management and the RIMT IOMMU mapping table. While deployments are still low today (most RISC-V hardware boots via devicetree), ACPI is the standardized firmware path for emerging server-class RISC-V platforms from vendors like Ventana, and there is no replacement driver — devicetree is an alternative, not a substitute.
repository signals
sources
- docs.kernel.org
Upstream kernel documentation has a dedicated, current 'ACPI on RISC-V' page, indicating supported in-tree functionality rather than legacy code.
- docs.kernel.org
Current RISC-V boot documentation states firmware may pass either devicetree or ACPI tables, so ACPI remains a live boot/configuration path for modern RISC-V systems.
- uefi.org
UEFI/ACPI standards added RISC-V support, showing this is an actively standardized platform model rather than obsolete hardware support.
- ventanamicro.com
Vendor material for current server-class RISC-V CPU/platform IP shows ongoing commercial development for new deployments in the 2025-2026 window.
codex reasoning notes (technical)
Local shell inspection showed this directory contains active ACPI/RISC-V platform code (e.g. device_initcall in cppc.c) and local git history shows substantive updates through 2026-03-03, with new RIMT and CPPC work rather than cleanup-only churn. URLs were obtained via web search/open for current kernel docs, UEFI standards news, and a current vendor page. No removal discussion was found in the limited lore-targeted web search, and the recent in-tree activity argues against deprecation. Deployments look low today because ACPI on RISC-V is still an emerging server/platform path, but it is clearly not obsolete and has no direct replacement driver; devicetree is an alternative firmware description path, not a drop-in replacement driver.