Linux 7.3 enforces timeout for EFI runtime service calls to prevent hangs

The Linux 7.3 kernel introduces a timeout for EFI runtime service calls, addressing a long-standing issue where buggy firmware could hang indefinitely. Previously, such hangs could propagate to user-space, causing system instability or crashes. The timeout ensures that if the firmware fails to respond, the kernel will abort the call rather than waiting forever. This is particularly relevant for systems where EFI firmware is unreliable or poorly tested, as it reduces the likelihood of cascading failures.

The change is defensive in nature, meaning it does not alter the expected behavior of well-functioning firmware. Instead, it acts as a safeguard against edge cases where firmware misbehaves. The timeout duration is not specified in the available material, but its enforcement implies a trade-off: systems may now fail faster in the presence of firmware bugs, rather than hanging indefinitely. This could improve debuggability but may also require adjustments in environments where firmware delays were previously tolerated.

For engineers deploying Linux on EFI-based hardware, this update reduces the operational risk of firmware-induced system freezes. However, it does not eliminate the root cause, buggy firmware, nor does it address other potential EFI-related issues. Systems with critical dependencies on EFI runtime services may still need additional validation to ensure compatibility with the new timeout behavior. The change is a step toward hardening the kernel against firmware flaws, but it remains a reactive measure rather than a fix for the underlying firmware problems.