Arm SMCCC (Secure Monitor Call Calling Convention) firmware interface
Implements the Arm-defined Secure Monitor Call Calling Convention, the standard way Linux on 32- and 64-bit Arm systems invokes secure firmware and hypervisors for power control, errata workarounds, SoC identification, and confidential-compute services. It underpins virtually every modern Arm phone, laptop, and server, including 2024–2025 cloud silicon like Microsoft's Azure Cobalt 100.
recommendation
It should stay because SMCCC is the standard calling convention every modern Arm system uses to talk to its secure firmware and hypervisor, and the code here is actively evolving. Recent 2025 and 2026 patches extend it for Arm Confidential Compute Architecture, KVM, and Hyper-V detection, and new Arm server silicon like Microsoft's Azure Cobalt 100 (GA October 2024) relies on this plumbing. There is no replacement because this is the architectural interface itself.
repository signals
sources
- lore.kernel.org
As of 2026-03-09, upstream was still adding/reshaping SMCCC platform-device support for Arm CCA auxiliary drivers, indicating active maintenance rather than retirement.
- lore.kernel.org
In 2025, upstream SMCCC work was still being extended for arm64/KVM and Hyper-V hypervisor UUID and presence detection, showing current deployment relevance in virtualized Arm systems.
- developer.arm.com
Arm documents SMCCC as a current architecture-standard firmware calling convention, so this directory implements architectural platform plumbing rather than a one-off obsolete device.
- azure.microsoft.com
Microsoft announced Azure Cobalt 100 Arm-based VMs as generally available in October 2024, evidencing ongoing new Arm server/cloud deployments in the 2025 era.
codex reasoning notes (technical)
Keep. Local tree inspection via shell showed this directory contains active Arm firmware-interface code (SMCCC core, KVM guest support, SoC ID bus exposure), not dead legacy glue. lore_file_timeline on smccc.c showed heavy recent activity through 2025-2026, including new CCA-related work; lore_substr_subject for 'smccc' surfaced 2025 Hyper-V/KVM integration patches. Web search produced the Arm SMCCC standards page and Azure Cobalt 100 GA page, supporting that SMCCC-backed Arm firmware/hypervisor environments are still shipping in new server/cloud deployments. No removal/deprecation evidence was found; there is no natural replacement driver because this is the architectural interface itself.