1.. SPDX-License-Identifier: GPL-2.0 OR GFDL-1.2-no-invariants-or-later 2 3================= 4EDAC/RAS features 5================= 6 7Copyright (c) 2024-2025 HiSilicon Limited. 8 9:Author: Shiju Jose <shiju.jose@huawei.com> 10:License: The GNU Free Documentation License, Version 1.2 without 11 Invariant Sections, Front-Cover Texts nor Back-Cover Texts. 12 (dual licensed under the GPL v2) 13 14- Written for: 6.15 15 16Introduction 17------------ 18 19EDAC/RAS components plugging and high-level design: 20 211. Scrub control 22 232. Error Check Scrub (ECS) control 24 253. ACPI RAS2 features 26 274. Post Package Repair (PPR) control 28 295. Memory Sparing Repair control 30 31High level design is illustrated in the following diagram:: 32 33 +-----------------------------------------------+ 34 | Userspace - Rasdaemon | 35 | +-------------+ | 36 | | RAS CXL mem | +---------------+ | 37 | |error handler|---->| | | 38 | +-------------+ | RAS dynamic | | 39 | +-------------+ | scrub, memory | | 40 | | RAS memory |---->| repair control| | 41 | |error handler| +----|----------+ | 42 | +-------------+ | | 43 +--------------------------|--------------------+ 44 | 45 | 46 +-------------------------------|------------------------------+ 47 | Kernel EDAC extension for | controlling RAS Features | 48 |+------------------------------|----------------------------+ | 49 || EDAC Core Sysfs EDAC| Bus | | 50 || +--------------------------|---------------------------+| | 51 || |/sys/bus/edac/devices/<dev>/scrubX/ | | EDAC device || | 52 || |/sys/bus/edac/devices/<dev>/ecsX/ |<->| EDAC MC || | 53 || |/sys/bus/edac/devices/<dev>/repairX | | EDAC sysfs || | 54 || +---------------------------|--------------------------+| | 55 || EDAC|Bus | | 56 || | | | 57 || +----------+ Get feature | Get feature | | 58 || | | desc +---------|------+ desc +----------+ | | 59 || |EDAC scrub|<-----| EDAC device | | | | | 60 || +----------+ | driver- RAS |----->| EDAC mem | | | 61 || +----------+ | feature control| | repair | | | 62 || | |<-----| | +----------+ | | 63 || |EDAC ECS | +---------|------+ | | 64 || +----------+ Register RAS|features | | 65 || ______________________|_____________ | | 66 |+---------|---------------|------------------|--------------+ | 67 | +-------|----+ +-------|-------+ +----|----------+ | 68 | | | | CXL mem driver| | Client driver | | 69 | | ACPI RAS2 | | scrub, ECS, | | memory repair | | 70 | | driver | | sparing, PPR | | features | | 71 | +-----|------+ +-------|-------+ +------|--------+ | 72 | | | | | 73 +--------|-----------------|--------------------|--------------+ 74 | | | 75 +--------|-----------------|--------------------|--------------+ 76 | +---|-----------------|--------------------|-------+ | 77 | | | | 78 | | Platform HW and Firmware | | 79 | +--------------------------------------------------+ | 80 +--------------------------------------------------------------+ 81 82 831. EDAC Features components - Create feature-specific descriptors. For 84 example: scrub, ECS, memory repair in the above diagram. 85 862. EDAC device driver for controlling RAS Features - Get feature's attribute 87 descriptors from EDAC RAS feature component and registers device's RAS 88 features with EDAC bus and expose the features control attributes via 89 sysfs. For example, /sys/bus/edac/devices/<dev-name>/<feature>X/ 90 913. RAS dynamic feature controller - Userspace sample modules in rasdaemon for 92 dynamic scrub/repair control to issue scrubbing/repair when excess number 93 of corrected memory errors are reported in a short span of time. 94 95RAS features 96------------ 971. Memory Scrub 98 99Memory scrub features are documented in `Documentation/edac/scrub.rst`. 100 1012. Memory Repair 102 103Memory repair features are documented in `Documentation/edac/memory_repair.rst`. 104