sphinx.addnodesdocument)}( rawsourcechildren]( translations LanguagesNode)}(hhh](h pending_xref)}(hhh]docutils.nodesTextChinese (Simplified)}parenthsba attributes}(ids]classes]names]dupnames]backrefs] refdomainstdreftypedoc reftarget/translations/zh_CN/edac/scrubmodnameN classnameN refexplicitutagnamehhh ubh)}(hhh]hChinese (Traditional)}hh2sbah}(h]h ]h"]h$]h&] refdomainh)reftypeh+ reftarget/translations/zh_TW/edac/scrubmodnameN classnameN refexplicituh1hhh ubh)}(hhh]hItalian}hhFsbah}(h]h ]h"]h$]h&] refdomainh)reftypeh+ reftarget/translations/it_IT/edac/scrubmodnameN classnameN refexplicituh1hhh ubh)}(hhh]hJapanese}hhZsbah}(h]h ]h"]h$]h&] refdomainh)reftypeh+ reftarget/translations/ja_JP/edac/scrubmodnameN classnameN refexplicituh1hhh ubh)}(hhh]hKorean}hhnsbah}(h]h ]h"]h$]h&] refdomainh)reftypeh+ reftarget/translations/ko_KR/edac/scrubmodnameN classnameN refexplicituh1hhh ubh)}(hhh]hPortuguese (Brazilian)}hhsbah}(h]h ]h"]h$]h&] refdomainh)reftypeh+ reftarget/translations/pt_BR/edac/scrubmodnameN classnameN refexplicituh1hhh ubh)}(hhh]hSpanish}hhsbah}(h]h ]h"]h$]h&] refdomainh)reftypeh+ reftarget/translations/sp_SP/edac/scrubmodnameN classnameN refexplicituh1hhh ubeh}(h]h ]h"]h$]h&]current_languageEnglishuh1h hh _documenthsourceNlineNubhcomment)}(hCSPDX-License-Identifier: GPL-2.0 OR GFDL-1.2-no-invariants-or-laterh]hCSPDX-License-Identifier: GPL-2.0 OR GFDL-1.2-no-invariants-or-later}hhsbah}(h]h ]h"]h$]h&] xml:spacepreserveuh1hhhhhh8/var/lib/git/docbuild/linux/Documentation/edac/scrub.rsthKubhsection)}(hhh](htitle)}(h Scrub Controlh]h Scrub Control}(hhhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhhhhhKubh paragraph)}(h*Copyright (c) 2024-2025 HiSilicon Limited.h]h*Copyright (c) 2024-2025 HiSilicon Limited.}(hhhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhhhhubh field_list)}(hhh](hfield)}(hhh](h field_name)}(hAuthorh]hAuthor}(hhhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhhhKubh field_body)}(h"Shiju Jose h]h)}(hj h](h Shiju Jose <}(hj hhhNhNubh reference)}(hshiju.jose@huawei.comh]hshiju.jose@huawei.com}(hjhhhNhNubah}(h]h ]h"]h$]h&]refurimailto:shiju.jose@huawei.comuh1jhj ubh>}(hj hhhNhNubeh}(h]h ]h"]h$]h&]uh1hhhhK hj ubah}(h]h ]h"]h$]h&]uh1jhhubeh}(h]h ]h"]h$]h&]uh1hhhhK hhhhubh)}(hhh](h)}(hLicenseh]hLicense}(hj?hhhNhNubah}(h]h ]h"]h$]h&]uh1hhj<hhhKubj)}(hThe GNU Free Documentation License, Version 1.2 without Invariant Sections, Front-Cover Texts nor Back-Cover Texts. (dual licensed under the GPL v2) h]h)}(hThe GNU Free Documentation License, Version 1.2 without Invariant Sections, Front-Cover Texts nor Back-Cover Texts. (dual licensed under the GPL v2)h]hThe GNU Free Documentation License, Version 1.2 without Invariant Sections, Front-Cover Texts nor Back-Cover Texts. (dual licensed under the GPL v2)}(hjQhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK hjMubah}(h]h ]h"]h$]h&]uh1jhj<ubeh}(h]h ]h"]h$]h&]uh1hhhhK hhhhubeh}(h]h ]h"]h$]h&]uh1hhhhhhhhK ubh bullet_list)}(hhh]h list_item)}(hWritten for: 6.15 h]h)}(hWritten for: 6.15h]hWritten for: 6.15}(hj|hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjxubah}(h]h ]h"]h$]h&]uh1jvhjshhhhhNubah}(h]h ]h"]h$]h&]bullet-uh1jqhhhKhhhhubh)}(hhh](h)}(h Introductionh]h Introduction}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjhhhhhKubh)}(hXIncreasing DRAM size and cost have made memory subsystem reliability an important concern. These modules are used where potentially corrupted data could cause expensive or fatal issues. Memory errors are among the top hardware failures that cause server and workload crashes.h]hXIncreasing DRAM size and cost have made memory subsystem reliability an important concern. These modules are used where potentially corrupted data could cause expensive or fatal issues. Memory errors are among the top hardware failures that cause server and workload crashes.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjhhubh)}(hMemory scrubbing is a feature where an ECC (Error-Correcting Code) engine reads data from each memory media location, corrects if necessary and writes the corrected data back to the same memory media location.h]hMemory scrubbing is a feature where an ECC (Error-Correcting Code) engine reads data from each memory media location, corrects if necessary and writes the corrected data back to the same memory media location.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjhhubh)}(hDIMMs can be scrubbed at a configurable rate to detect uncorrected memory errors and attempt recovery from detected errors, providing the following benefits:h]hDIMMs can be scrubbed at a configurable rate to detect uncorrected memory errors and attempt recovery from detected errors, providing the following benefits:}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjhhubhenumerated_list)}(hhh](jw)}(h^Proactively scrubbing DIMMs reduces the chance of a correctable error becoming uncorrectable. h]h)}(h]Proactively scrubbing DIMMs reduces the chance of a correctable error becoming uncorrectable.h]h]Proactively scrubbing DIMMs reduces the chance of a correctable error becoming uncorrectable.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK hjubah}(h]h ]h"]h$]h&]uh1jvhjhhhhhNubjw)}(hWhen detected, uncorrected errors caught in unallocated memory pages are isolated and prevented from being allocated to an application or the OS. h]h)}(hWhen detected, uncorrected errors caught in unallocated memory pages are isolated and prevented from being allocated to an application or the OS.h]hWhen detected, uncorrected errors caught in unallocated memory pages are isolated and prevented from being allocated to an application or the OS.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK#hjubah}(h]h ]h"]h$]h&]uh1jvhjhhhhhNubjw)}(hYThis reduces the likelihood of software or hardware products encountering memory errors. h]h)}(hXThis reduces the likelihood of software or hardware products encountering memory errors.h]hXThis reduces the likelihood of software or hardware products encountering memory errors.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK&hjubah}(h]h ]h"]h$]h&]uh1jvhjhhhhhNubjw)}(hThe additional data on failures in memory may be used to build up statistics that are later used to decide whether to use memory repair technologies such as Post Package Repair or Sparing. h]h)}(hThe additional data on failures in memory may be used to build up statistics that are later used to decide whether to use memory repair technologies such as Post Package Repair or Sparing.h]hThe additional data on failures in memory may be used to build up statistics that are later used to decide whether to use memory repair technologies such as Post Package Repair or Sparing.}(hj$hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK)hj ubah}(h]h ]h"]h$]h&]uh1jvhjhhhhhNubeh}(h]h ]h"]h$]h&]enumtypearabicprefixhsuffix.uh1jhjhhhhhK ubh)}(h&There are 2 types of memory scrubbing:h]h&There are 2 types of memory scrubbing:}(hjChhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK-hjhhubj)}(hhh](jw)}(h@Background (patrol) scrubbing while the DRAM is otherwise idle. h]h)}(h?Background (patrol) scrubbing while the DRAM is otherwise idle.h]h?Background (patrol) scrubbing while the DRAM is otherwise idle.}(hjXhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK/hjTubah}(h]h ]h"]h$]h&]uh1jvhjQhhhhhNubjw)}(hFOn-demand scrubbing for a specific address range or region of memory. h]h)}(hEOn-demand scrubbing for a specific address range or region of memory.h]hEOn-demand scrubbing for a specific address range or region of memory.}(hjphhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK1hjlubah}(h]h ]h"]h$]h&]uh1jvhjQhhhhhNubeh}(h]h ]h"]h$]h&]j>j?j@hjAjBuh1jhjhhhhhK/ubh)}(hSeveral types of interfaces to hardware memory scrubbers have been identified, such as CXL memory device patrol scrub, CXL DDR5 ECS, ACPI RAS2 memory scrubbing, and ACPI NVDIMM ARS (Address Range Scrub).h]hSeveral types of interfaces to hardware memory scrubbers have been identified, such as CXL memory device patrol scrub, CXL DDR5 ECS, ACPI RAS2 memory scrubbing, and ACPI NVDIMM ARS (Address Range Scrub).}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK3hjhhubh)}(hThe control mechanisms vary across different memory scrubbers. To enable standardized userspace tooling, there is a need to present these controls through a standardized ABI.h]hThe control mechanisms vary across different memory scrubbers. To enable standardized userspace tooling, there is a need to present these controls through a standardized ABI.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK7hjhhubh)}(hA generic memory EDAC scrub control allows users to manage underlying scrubbers in the system through a standardized sysfs control interface. It abstracts the management of various scrubbing functionalities into a unified set of functions.h]hA generic memory EDAC scrub control allows users to manage underlying scrubbers in the system through a standardized sysfs control interface. It abstracts the management of various scrubbing functionalities into a unified set of functions.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK;hjhhubeh}(h] introductionah ]h"] introductionah$]h&]uh1hhhhhhhhKubh)}(hhh](h)}(h)Use cases of common scrub control featureh]h)Use cases of common scrub control feature}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjhhhhhKAubj)}(hhh](jw)}(hXSeveral types of interfaces for hardware memory scrubbers have been identified, including the CXL memory device patrol scrub, CXL DDR5 ECS, ACPI RAS2 memory scrubbing features, ACPI NVDIMM ARS (Address Range Scrub), and software-based memory scrubbers. Of the identified interfaces to hardware memory scrubbers some support control over patrol (background) scrubbing (e.g., ACPI RAS2, CXL) and/or on-demand scrubbing (e.g., ACPI RAS2, ACPI ARS). However, the scrub control interfaces vary between memory scrubbers, highlighting the need for a standardized, generic sysfs scrub control interface that is accessible to userspace for administration and use by scripts/tools. h](h)}(hSeveral types of interfaces for hardware memory scrubbers have been identified, including the CXL memory device patrol scrub, CXL DDR5 ECS, ACPI RAS2 memory scrubbing features, ACPI NVDIMM ARS (Address Range Scrub), and software-based memory scrubbers.h]hSeveral types of interfaces for hardware memory scrubbers have been identified, including the CXL memory device patrol scrub, CXL DDR5 ECS, ACPI RAS2 memory scrubbing features, ACPI NVDIMM ARS (Address Range Scrub), and software-based memory scrubbers.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKChjubh)}(hXOf the identified interfaces to hardware memory scrubbers some support control over patrol (background) scrubbing (e.g., ACPI RAS2, CXL) and/or on-demand scrubbing (e.g., ACPI RAS2, ACPI ARS). However, the scrub control interfaces vary between memory scrubbers, highlighting the need for a standardized, generic sysfs scrub control interface that is accessible to userspace for administration and use by scripts/tools.h]hXOf the identified interfaces to hardware memory scrubbers some support control over patrol (background) scrubbing (e.g., ACPI RAS2, CXL) and/or on-demand scrubbing (e.g., ACPI RAS2, ACPI ARS). However, the scrub control interfaces vary between memory scrubbers, highlighting the need for a standardized, generic sysfs scrub control interface that is accessible to userspace for administration and use by scripts/tools.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKHhjubeh}(h]h ]h"]h$]h&]uh1jvhjhhhhhNubjw)}(hUser-space scrub controls allow users to disable scrubbing if necessary, for example, to disable background patrol scrubbing or adjust the scrub rate for performance-aware operations where background activities need to be minimized or disabled. h]h)}(hUser-space scrub controls allow users to disable scrubbing if necessary, for example, to disable background patrol scrubbing or adjust the scrub rate for performance-aware operations where background activities need to be minimized or disabled.h]hUser-space scrub controls allow users to disable scrubbing if necessary, for example, to disable background patrol scrubbing or adjust the scrub rate for performance-aware operations where background activities need to be minimized or disabled.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKOhjubah}(h]h ]h"]h$]h&]uh1jvhjhhhhhNubjw)}(hUser-space tools enable on-demand scrubbing for specific address ranges, provided that the scrubber supports this functionality. h]h)}(hUser-space tools enable on-demand scrubbing for specific address ranges, provided that the scrubber supports this functionality.h]hUser-space tools enable on-demand scrubbing for specific address ranges, provided that the scrubber supports this functionality.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKThjubah}(h]h ]h"]h$]h&]uh1jvhjhhhhhNubjw)}(hXnUser-space tools can also control memory DIMM scrubbing at a configurable scrub rate via sysfs scrub controls. This approach offers several benefits: 4.1. Detects uncorrectable memory errors early, before user access to affected memory, helping facilitate recovery. 4.2. Reduces the likelihood of correctable errors developing into uncorrectable errors. h](h)}(hUser-space tools can also control memory DIMM scrubbing at a configurable scrub rate via sysfs scrub controls. This approach offers several benefits:h]hUser-space tools can also control memory DIMM scrubbing at a configurable scrub rate via sysfs scrub controls. This approach offers several benefits:}(hj*hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKWhj&ubhdefinition_list)}(hhh](hdefinition_list_item)}(ht4.1. Detects uncorrectable memory errors early, before user access to affected memory, helping facilitate recovery. h](hterm)}(hN4.1. Detects uncorrectable memory errors early, before user access to affectedh]hN4.1. Detects uncorrectable memory errors early, before user access to affected}(hjEhhhNhNubah}(h]h ]h"]h$]h&]uh1jChhhK[hj?ubh definition)}(hhh]h)}(h$memory, helping facilitate recovery.h]h$memory, helping facilitate recovery.}(hjXhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK[hjUubah}(h]h ]h"]h$]h&]uh1jShj?ubeh}(h]h ]h"]h$]h&]uh1j=hhhK[hj:ubj>)}(hX4.2. Reduces the likelihood of correctable errors developing into uncorrectable errors. h](jD)}(hO4.2. Reduces the likelihood of correctable errors developing into uncorrectableh]hO4.2. Reduces the likelihood of correctable errors developing into uncorrectable}(hjvhhhNhNubah}(h]h ]h"]h$]h&]uh1jChhhK^hjrubjT)}(hhh]h)}(herrors.h]herrors.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK^hjubah}(h]h ]h"]h$]h&]uh1jShjrubeh}(h]h ]h"]h$]h&]uh1j=hhhK^hj:ubeh}(h]h ]h"]h$]h&]uh1j8hj&ubeh}(h]h ]h"]h$]h&]uh1jvhjhhhNhNubjw)}(hXPolicy control for hotplugged memory is necessary because there may not be a system-wide BIOS or similar control to manage scrub settings for a CXL device added after boot. Determining these settings is a policy decision, balancing reliability against performance, so userspace should control it. Therefore, a unified interface is recommended for handling this function in a way that aligns with other similar interfaces, rather than creating a separate one. h]h)}(hXPolicy control for hotplugged memory is necessary because there may not be a system-wide BIOS or similar control to manage scrub settings for a CXL device added after boot. Determining these settings is a policy decision, balancing reliability against performance, so userspace should control it. Therefore, a unified interface is recommended for handling this function in a way that aligns with other similar interfaces, rather than creating a separate one.h]hXPolicy control for hotplugged memory is necessary because there may not be a system-wide BIOS or similar control to manage scrub settings for a CXL device added after boot. Determining these settings is a policy decision, balancing reliability against performance, so userspace should control it. Therefore, a unified interface is recommended for handling this function in a way that aligns with other similar interfaces, rather than creating a separate one.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK`hjubah}(h]h ]h"]h$]h&]uh1jvhjhhhhhNubeh}(h]h ]h"]h$]h&]j>j?j@hjAjBuh1jhjhhhhhKCubeh}(h])use-cases-of-common-scrub-control-featureah ]h"])use cases of common scrub control featureah$]h&]uh1hhhhhhhhKAubh)}(hhh](h)}(hScrubbing featuresh]hScrubbing features}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjhhhhhKiubh)}(hhh](h)}(hCXL Memory Scrubbing featuresh]hCXL Memory Scrubbing features}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjhhhhhKlubh)}(hX%CXL spec r3.1 [1]_ section 8.2.9.9.11.1 describes the memory device patrol scrub control feature. The device patrol scrub proactively locates and makes corrections to errors in regular cycle. The patrol scrub control allows the userspace request to change CXL patrol scrubber's configurations.h](hCXL spec r3.1 }(hjhhhNhNubhfootnote_reference)}(h[1]_h]h1}(hjhhhNhNubah}(h]id1ah ]h"]h$]h&]refidid5docname edac/scrubuh1jhjresolvedKubhX section 8.2.9.9.11.1 describes the memory device patrol scrub control feature. The device patrol scrub proactively locates and makes corrections to errors in regular cycle. The patrol scrub control allows the userspace request to change CXL patrol scrubber’s configurations.}(hjhhhNhNubeh}(h]h ]h"]h$]h&]uh1hhhhKnhjhhubh)}(hX|The patrol scrub control allows the requester to specify the number of hours in which the patrol scrub cycles must be completed, provided that the requested scrub rate must be within the supported range of the scrub rate that the device is capable of. In the CXL driver, the number of seconds per scrub cycles, which user requests via sysfs, is rescaled to hours per scrub cycles.h]hX|The patrol scrub control allows the requester to specify the number of hours in which the patrol scrub cycles must be completed, provided that the requested scrub rate must be within the supported range of the scrub rate that the device is capable of. In the CXL driver, the number of seconds per scrub cycles, which user requests via sysfs, is rescaled to hours per scrub cycles.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKshjhhubh)}(hIn addition, they allow the host to disable the feature in case it interferes with performance-aware operations which require the background operations to be turned off.h]hIn addition, they allow the host to disable the feature in case it interferes with performance-aware operations which require the background operations to be turned off.}(hj+hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKzhjhhubeh}(h]cxl-memory-scrubbing-featuresah ]h"]cxl memory scrubbing featuresah$]h&]uh1hhjhhhhhKlubh)}(hhh](h)}(hError Check Scrub (ECS)h]hError Check Scrub (ECS)}(hjDhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjAhhhhhKubh)}(hX2CXL spec r3.1 [1]_ section 8.2.9.9.11.2 describes Error Check Scrub (ECS) - a feature defined in the JEDEC DDR5 SDRAM Specification (JESD79-5) and allowing DRAM to internally read, correct single-bit errors, and write back corrected data bits to the DRAM array while providing transparency to error counts.h](hCXL spec r3.1 }(hjRhhhNhNubj)}(h[1]_h]h1}(hjZhhhNhNubah}(h]id2ah ]h"]h$]h&]jjjjuh1jhjRjKubhX  section 8.2.9.9.11.2 describes Error Check Scrub (ECS) - a feature defined in the JEDEC DDR5 SDRAM Specification (JESD79-5) and allowing DRAM to internally read, correct single-bit errors, and write back corrected data bits to the DRAM array while providing transparency to error counts.}(hjRhhhNhNubeh}(h]h ]h"]h$]h&]uh1hhhhKhjAhhubh)}(hThe DDR5 device contains number of memory media Field Replaceable Units (FRU) per device. The DDR5 ECS feature and thus the ECS control driver supports configuring the ECS parameters per FRU.h]hThe DDR5 device contains number of memory media Field Replaceable Units (FRU) per device. The DDR5 ECS feature and thus the ECS control driver supports configuring the ECS parameters per FRU.}(hjshhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjAhhubeh}(h]error-check-scrub-ecsah ]h"]error check scrub (ecs)ah$]h&]uh1hhjhhhhhKubh)}(hhh](h)}(h)ACPI RAS2 Hardware-based Memory Scrubbingh]h)ACPI RAS2 Hardware-based Memory Scrubbing}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjhhhhhKubh)}(hX ACPI spec 6.5 [2]_ section 5.2.21 ACPI RAS2 describes an ACPI RAS2 table which provides interfaces for platform RAS features and supports independent RAS controls and capabilities for a given RAS feature for multiple instances of the same component in a given system.h](hACPI spec 6.5 }(hjhhhNhNubj)}(h[2]_h]h2}(hjhhhNhNubah}(h]id3ah ]h"]h$]h&]jid6jjuh1jhjjKubh section 5.2.21 ACPI RAS2 describes an ACPI RAS2 table which provides interfaces for platform RAS features and supports independent RAS controls and capabilities for a given RAS feature for multiple instances of the same component in a given system.}(hjhhhNhNubeh}(h]h ]h"]h$]h&]uh1hhhhKhjhhubh)}(hMemory RAS features apply to RAS capabilities, controls and operations that are specific to memory. RAS2 PCC sub-spaces for memory-specific RAS features have a Feature Type of 0x00 (Memory).h]hMemory RAS features apply to RAS capabilities, controls and operations that are specific to memory. RAS2 PCC sub-spaces for memory-specific RAS features have a Feature Type of 0x00 (Memory).}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjhhubh)}(hThe platform can use the hardware-based memory scrubbing feature to expose controls and capabilities associated with hardware-based memory scrub engines. The RAS2 memory scrubbing feature supports as per spec,h]hThe platform can use the hardware-based memory scrubbing feature to expose controls and capabilities associated with hardware-based memory scrub engines. The RAS2 memory scrubbing feature supports as per spec,}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjhhubj)}(hhh](jw)}(hcIndependent memory scrubbing controls for each NUMA domain, identified using its proximity domain. h]h)}(hbIndependent memory scrubbing controls for each NUMA domain, identified using its proximity domain.h]hbIndependent memory scrubbing controls for each NUMA domain, identified using its proximity domain.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjhhhhhNubjw)}(hProvision for background (patrol) scrubbing of the entire memory system, as well as on-demand scrubbing for a specific region of memory. h]h)}(hProvision for background (patrol) scrubbing of the entire memory system, as well as on-demand scrubbing for a specific region of memory.h]hProvision for background (patrol) scrubbing of the entire memory system, as well as on-demand scrubbing for a specific region of memory.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjhhhhhNubeh}(h]h ]h"]h$]h&]j>j?j@hjAjBuh1jhjhhhhhKubeh}(h])acpi-ras2-hardware-based-memory-scrubbingah ]h"])acpi ras2 hardware-based memory scrubbingah$]h&]uh1hhjhhhhhKubh)}(hhh](h)}(h"ACPI Address Range Scrubbing (ARS)h]h"ACPI Address Range Scrubbing (ARS)}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjhhhhhKubh)}(hX{ACPI spec 6.5 [2]_ section 9.19.7.2 describes Address Range Scrubbing (ARS). ARS allows the platform to communicate memory errors to system software. This capability allows system software to prevent accesses to addresses with uncorrectable errors in memory. ARS functions manage all NVDIMMs present in the system. Only one scrub can be in progress system wide at any given time.h](hACPI spec 6.5 }(hj*hhhNhNubj)}(h[2]_h]h2}(hj2hhhNhNubah}(h]id4ah ]h"]h$]h&]jjjjuh1jhj*jKubhXi section 9.19.7.2 describes Address Range Scrubbing (ARS). ARS allows the platform to communicate memory errors to system software. This capability allows system software to prevent accesses to addresses with uncorrectable errors in memory. ARS functions manage all NVDIMMs present in the system. Only one scrub can be in progress system wide at any given time.}(hj*hhhNhNubeh}(h]h ]h"]h$]h&]uh1hhhhKhjhhubh)}(h?The following functions are supported as per the specification:h]h?The following functions are supported as per the specification:}(hjKhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjhhubj)}(hhh](jw)}(hQuery ARS Capabilities for a given address range, indicates platform supports the ACPI NVDIMM Root Device Unconsumed Error Notification. h]h)}(hQuery ARS Capabilities for a given address range, indicates platform supports the ACPI NVDIMM Root Device Unconsumed Error Notification.h]hQuery ARS Capabilities for a given address range, indicates platform supports the ACPI NVDIMM Root Device Unconsumed Error Notification.}(hj`hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj\ubah}(h]h ]h"]h$]h&]uh1jvhjYhhhhhNubjw)}(hStart ARS triggers an Address Range Scrub for the given memory range. Address scrubbing can be done for volatile or persistent memory, or both. h]h)}(hStart ARS triggers an Address Range Scrub for the given memory range. Address scrubbing can be done for volatile or persistent memory, or both.h]hStart ARS triggers an Address Range Scrub for the given memory range. Address scrubbing can be done for volatile or persistent memory, or both.}(hjxhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjtubah}(h]h ]h"]h$]h&]uh1jvhjYhhhhhNubjw)}(hwQuery ARS Status command allows software to get the status of ARS, including the progress of ARS and ARS error record. h]h)}(hvQuery ARS Status command allows software to get the status of ARS, including the progress of ARS and ARS error record.h]hvQuery ARS Status command allows software to get the status of ARS, including the progress of ARS and ARS error record.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjYhhhhhNubjw)}(hClear Uncorrectable Error. h]h)}(hClear Uncorrectable Error.h]hClear Uncorrectable Error.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjYhhhhhNubjw)}(hTranslate SPA h]h)}(h Translate SPAh]h Translate SPA}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjYhhhhhNubjw)}(hARS Error Inject etc. h]h)}(hARS Error Inject etc.h]hARS Error Inject etc.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjYhhhhhNubeh}(h]h ]h"]h$]h&]j>j?j@hjAjBuh1jhjhhhhhKubh)}(h[The kernel supports an existing control for ARS and ARS is currently not supported in EDAC.h]h[The kernel supports an existing control for ARS and ARS is currently not supported in EDAC.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjhhubhfootnote)}(h2https://computeexpresslink.org/cxl-specification/ h](hlabel)}(h1h]h1}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jhjubh)}(h1https://computeexpresslink.org/cxl-specification/h]j)}(hjh]h1https://computeexpresslink.org/cxl-specification/}(hjhhhNhNubah}(h]h ]h"]h$]h&]refurijuh1jhjubah}(h]h ]h"]h$]h&]uh1hhhhKhjubeh}(h]jah ]h"]1ah$]h&](j jdejjuh1jhhhKhjhhjKubj)}(h!https://uefi.org/specs/ACPI/6.5/ h](j)}(h2h]h2}(hj9hhhNhNubah}(h]h ]h"]h$]h&]uh1jhj5ubh)}(h https://uefi.org/specs/ACPI/6.5/h]j)}(hjIh]h https://uefi.org/specs/ACPI/6.5/}(hjKhhhNhNubah}(h]h ]h"]h$]h&]refurijIuh1jhjGubah}(h]h ]h"]h$]h&]uh1hhhhKhj5ubeh}(h]jah ]h"]2ah$]h&](jj<ejjuh1jhhhKhjhhjKubeh}(h] acpi-address-range-scrubbing-arsah ]h"]"acpi address range scrubbing (ars)ah$]h&]uh1hhjhhhhhKubh)}(hhh](h)}(h(Comparison of various scrubbing featuresh]h(Comparison of various scrubbing features}(hjqhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjnhhhhhKubh block_quote)}(hX +--------------+-----------+-----------+-----------+-----------+ | | ACPI | CXL patrol| CXL ECS | ARS | | Name | RAS2 | scrub | | | +--------------+-----------+-----------+-----------+-----------+ | | | | | | | On-demand | Supported | No | No | Supported | | Scrubbing | | | | | | | | | | | +--------------+-----------+-----------+-----------+-----------+ | | | | | | | Background | Supported | Supported | Supported | No | | scrubbing | | | | | | | | | | | +--------------+-----------+-----------+-----------+-----------+ | | | | | | | Mode of | Scrub ctrl| per device| per memory| Unknown | | scrubbing | per NUMA | | media | | | | domain. | | | | +--------------+-----------+-----------+-----------+-----------+ | | | | | | | Query scrub | Supported | Supported | Supported | Supported | | capabilities | | | | | | | | | | | +--------------+-----------+-----------+-----------+-----------+ | | | | | | | Setting | Supported | No | No | Supported | | address range| | | | | | | | | | | +--------------+-----------+-----------+-----------+-----------+ | | | | | | | Setting | Supported | Supported | No | No | | scrub rate | | | | | | | | | | | +--------------+-----------+-----------+-----------+-----------+ | | | | | | | Unit for | Not | in hours | No | No | | scrub rate | Defined | | | | | | | | | | +--------------+-----------+-----------+-----------+-----------+ | | Supported | | | | | Scrub | on-demand | No | No | Supported | | status/ | scrubbing | | | | | Completion | only | | | | +--------------+-----------+-----------+-----------+-----------+ | UC error | |CXL general|CXL general| ACPI UCE | | reporting | Exception |media/DRAM |media/DRAM | notify and| | | |event/media|event/media| query | | | |scan? |scan? | ARS status| +--------------+-----------+-----------+-----------+-----------+ | | | | | | | Support for | Supported | Supported | Supported | No | | EDAC control | | | | | | | | | | | +--------------+-----------+-----------+-----------+-----------+ h]htable)}(hhh]htgroup)}(hhh](hcolspec)}(hhh]h}(h]h ]h"]h$]h&]colwidthKuh1jhjubj)}(hhh]h}(h]h ]h"]h$]h&]colwidthK uh1jhjubj)}(hhh]h}(h]h ]h"]h$]h&]colwidthK uh1jhjubj)}(hhh]h}(h]h ]h"]h$]h&]colwidthK uh1jhjubj)}(hhh]h}(h]h ]h"]h$]h&]colwidthK uh1jhjubhtbody)}(hhh](hrow)}(hhh](hentry)}(hhh]h)}(hNameh]hName}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh]h)}(h ACPI RAS2h]h ACPI RAS2}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh]h)}(hCXL patrol scrubh]hCXL patrol scrub}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh]h)}(hCXL ECSh]hCXL ECS}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh]h)}(hARSh]hARS}(hj.hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj+ubah}(h]h ]h"]h$]h&]uh1jhjubeh}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh](j)}(hhh]h)}(hOn-demand Scrubbingh]hOn-demand Scrubbing}(hjNhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjKubah}(h]h ]h"]h$]h&]uh1jhjHubj)}(hhh]h)}(h Supportedh]h Supported}(hjehhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjbubah}(h]h ]h"]h$]h&]uh1jhjHubj)}(hhh]h)}(hNoh]hNo}(hj|hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjyubah}(h]h ]h"]h$]h&]uh1jhjHubj)}(hhh]h)}(hNoh]hNo}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jhjHubj)}(hhh]h)}(h Supportedh]h Supported}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jhjHubeh}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh](j)}(hhh]h)}(hBackground scrubbingh]hBackground scrubbing}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh]h)}(h Supportedh]h Supported}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh]h)}(h Supportedh]h Supported}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh]h)}(h Supportedh]h Supported}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh]h)}(hNoh]hNo}(hj&hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj#ubah}(h]h ]h"]h$]h&]uh1jhjubeh}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh](j)}(hhh]h)}(hMode of scrubbingh]hMode of scrubbing}(hjFhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjCubah}(h]h ]h"]h$]h&]uh1jhj@ubj)}(hhh]h)}(hScrub ctrl per NUMA domain.h]hScrub ctrl per NUMA domain.}(hj]hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjZubah}(h]h ]h"]h$]h&]uh1jhj@ubj)}(hhh]h)}(h per deviceh]h per device}(hjthhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjqubah}(h]h ]h"]h$]h&]uh1jhj@ubj)}(hhh]h)}(hper memory mediah]hper memory media}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jhj@ubj)}(hhh]h)}(hUnknownh]hUnknown}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jhj@ubeh}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh](j)}(hhh]h)}(hQuery scrub capabilitiesh]hQuery scrub capabilities}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh]h)}(h Supportedh]h Supported}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh]h)}(h Supportedh]h Supported}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh]h)}(h Supportedh]h Supported}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh]h)}(h Supportedh]h Supported}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhjubeh}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh](j)}(hhh]h)}(hSetting address rangeh]hSetting address range}(hj> hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj; ubah}(h]h ]h"]h$]h&]uh1jhj8 ubj)}(hhh]h)}(h Supportedh]h Supported}(hjU hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjR ubah}(h]h ]h"]h$]h&]uh1jhj8 ubj)}(hhh]h)}(hNoh]hNo}(hjl hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhji ubah}(h]h ]h"]h$]h&]uh1jhj8 ubj)}(hhh]h)}(hNoh]hNo}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhj8 ubj)}(hhh]h)}(h Supportedh]h Supported}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhj8 ubeh}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh](j)}(hhh]h)}(hSetting scrub rateh]hSetting scrub rate}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhj ubj)}(hhh]h)}(h Supportedh]h Supported}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhj ubj)}(hhh]h)}(h Supportedh]h Supported}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhj ubj)}(hhh]h)}(hNoh]hNo}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhj ubj)}(hhh]h)}(hNoh]hNo}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhj ubeh}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh](j)}(hhh]h)}(hUnit for scrub rateh]hUnit for scrub rate}(hj6 hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj3 ubah}(h]h ]h"]h$]h&]uh1jhj0 ubj)}(hhh]h)}(h Not Definedh]h Not Defined}(hjM hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjJ ubah}(h]h ]h"]h$]h&]uh1jhj0 ubj)}(hhh]h)}(hin hoursh]hin hours}(hjd hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhja ubah}(h]h ]h"]h$]h&]uh1jhj0 ubj)}(hhh]h)}(hNoh]hNo}(hj{ hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjx ubah}(h]h ]h"]h$]h&]uh1jhj0 ubj)}(hhh]h)}(hNoh]hNo}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhj0 ubeh}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh](j)}(hhh]h)}(hScrub status/ Completionh]hScrub status/ Completion}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhj ubj)}(hhh]h)}(h"Supported on-demand scrubbing onlyh]h"Supported on-demand scrubbing only}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhj ubj)}(hhh]h)}(hNoh]hNo}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhj ubj)}(hhh]h)}(hNoh]hNo}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhj ubj)}(hhh]h)}(h Supportedh]h Supported}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhj ubeh}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh](j)}(hhh]h)}(hUC error reportingh]hUC error reporting}(hj. hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj+ ubah}(h]h ]h"]h$]h&]uh1jhj( ubj)}(hhh]h)}(h Exceptionh]h Exception}(hjE hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjB ubah}(h]h ]h"]h$]h&]uh1jhj( ubj)}(hhh]h)}(h(CXL general media/DRAM event/media scan?h]h(CXL general media/DRAM event/media scan?}(hj\ hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjY ubah}(h]h ]h"]h$]h&]uh1jhj( ubj)}(hhh]h)}(h(CXL general media/DRAM event/media scan?h]h(CXL general media/DRAM event/media scan?}(hjs hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjp ubah}(h]h ]h"]h$]h&]uh1jhj( ubj)}(hhh]h)}(h$ACPI UCE notify and query ARS statush]h$ACPI UCE notify and query ARS status}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhj( ubeh}(h]h ]h"]h$]h&]uh1jhjubj)}(hhh](j)}(hhh]h)}(hSupport for EDAC controlh]hSupport for EDAC control}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhj ubj)}(hhh]h)}(h Supportedh]h Supported}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhj ubj)}(hhh]h)}(h Supportedh]h Supported}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhj ubj)}(hhh]h)}(h Supportedh]h Supported}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhj ubj)}(hhh]h)}(hNoh]hNo}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jhj ubeh}(h]h ]h"]h$]h&]uh1jhjubeh}(h]h ]h"]h$]h&]uh1jhjubeh}(h]h ]h"]h$]h&]colsKuh1jhjubah}(h]h ]h"]h$]h&]uh1jhjubah}(h]h ]h"]h$]h&]uh1jhhhKhjnhhubeh}(h](comparison-of-various-scrubbing-featuresah ]h"](comparison of various scrubbing featuresah$]h&]uh1hhjhhhhhKubeh}(h]scrubbing-featuresah ]h"]scrubbing featuresah$]h&]uh1hhhhhhhhKiubh)}(hhh](h)}(hThe File Systemh]hThe File System}(hjL hhhNhNubah}(h]h ]h"]h$]h&]uh1hhjI hhhhhKubh)}(hNThe control attributes of a registered scrubber instance could be accessed in:h]hNThe control attributes of a registered scrubber instance could be accessed in:}(hjZ hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjI hhubh)}(h(/sys/bus/edac/devices//scrubX/h]h(/sys/bus/edac/devices//scrubX/}(hjh hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjI hhubeh}(h]the-file-systemah ]h"]the file systemah$]h&]uh1hhhhhhhhKubh)}(hhh](h)}(hsysfsh]hsysfs}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhj~ hhhhhMubh)}(hJSysfs files are documented in `Documentation/ABI/testing/sysfs-edac-scrub`h](hSysfs files are documented in }(hj hhhNhNubhtitle_reference)}(h,`Documentation/ABI/testing/sysfs-edac-scrub`h]h*Documentation/ABI/testing/sysfs-edac-scrub}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1j hj ubeh}(h]h ]h"]h$]h&]uh1hhhhMhj~ hhubh)}(h*`Documentation/ABI/testing/sysfs-edac-ecs`h]j )}(hj h]h(Documentation/ABI/testing/sysfs-edac-ecs}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1j hj ubah}(h]h ]h"]h$]h&]uh1hhhhM hj~ hhubeh}(h]sysfsah ]h"]sysfsah$]h&]uh1hhhhhhhhMubh)}(hhh](h)}(hExamplesh]hExamples}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhj hhhhhM ubh)}(h1The usage takes the form shown in these examples:h]h1The usage takes the form shown in these examples:}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj hhubj)}(hhh]jw)}(hCXL memory Patrol Scrub h]h)}(hCXL memory Patrol Scrubh]hCXL memory Patrol Scrub}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj ubah}(h]h ]h"]h$]h&]uh1jvhj hhhhhNubah}(h]h ]h"]h$]h&]j>j?j@hjAjBuh1jhj hhhhhMubh)}(hPThe following are the use cases identified why we might increase the scrub rate.h]hPThe following are the use cases identified why we might increase the scrub rate.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj hhubjr)}(hhh](jw)}(h`Scrubbing is needed at device granularity because a device is showing unexpectedly high errors. h]h)}(h_Scrubbing is needed at device granularity because a device is showing unexpectedly high errors.h]h_Scrubbing is needed at device granularity because a device is showing unexpectedly high errors.}(hj! hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj ubah}(h]h ]h"]h$]h&]uh1jvhj hhhhhNubjw)}(hrScrubbing may apply to memory that isn't online at all yet. Likely this is a system wide default setting on boot. h]h)}(hqScrubbing may apply to memory that isn't online at all yet. Likely this is a system wide default setting on boot.h]hsScrubbing may apply to memory that isn’t online at all yet. Likely this is a system wide default setting on boot.}(hj9 hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj5 ubah}(h]h ]h"]h$]h&]uh1jvhj hhhhhNubjw)}(hScrubbing at a higher rate because the monitor software has determined that more reliability is necessary for a particular data set. This is called Differentiated Reliability. h]h)}(hScrubbing at a higher rate because the monitor software has determined that more reliability is necessary for a particular data set. This is called Differentiated Reliability.h]hScrubbing at a higher rate because the monitor software has determined that more reliability is necessary for a particular data set. This is called Differentiated Reliability.}(hjQ hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjM ubah}(h]h ]h"]h$]h&]uh1jvhj hhhhhNubeh}(h]h ]h"]h$]h&]jjuh1jqhhhMhj hhubh)}(h1.1. Device based scrubbingh]h1.1. Device based scrubbing}(hjk hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj hhubh)}(hCXL memory is exposed to memory management subsystem and ultimately userspace via CXL devices. Device-based scrubbing is used for the first use case described in "Section 1 CXL Memory Patrol Scrub".h]hCXL memory is exposed to memory management subsystem and ultimately userspace via CXL devices. Device-based scrubbing is used for the first use case described in “Section 1 CXL Memory Patrol Scrub”.}(hjy hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM!hj hhubh)}(hqWhen combining control via the device interfaces and region interfaces, "see Section 1.2 Region based scrubbing".h]huWhen combining control via the device interfaces and region interfaces, “see Section 1.2 Region based scrubbing”.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM%hj hhubh)}(hXSysfs files for scrubbing are documented in `Documentation/ABI/testing/sysfs-edac-scrub`h](h,Sysfs files for scrubbing are documented in }(hj hhhNhNubj )}(h,`Documentation/ABI/testing/sysfs-edac-scrub`h]h*Documentation/ABI/testing/sysfs-edac-scrub}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1j hj ubeh}(h]h ]h"]h$]h&]uh1hhhhM(hj hhubh)}(h1.2. Region based scrubbingh]h1.2. Region based scrubbing}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM+hj hhubh)}(hXCXL memory is exposed to memory management subsystem and ultimately userspace via CXL regions. CXL Regions represent mapped memory capacity in system physical address space. These can incorporate one or more parts of multiple CXL memory devices with traffic interleaved across them. The user may want to control the scrub rate via this more abstract region instead of having to figure out the constituent devices and program them separately. The scrub rate for each device covers the whole device. Thus if multiple regions use parts of that device then requests for scrubbing of other regions may result in a higher scrub rate than requested for this specific region.h]hXCXL memory is exposed to memory management subsystem and ultimately userspace via CXL regions. CXL Regions represent mapped memory capacity in system physical address space. These can incorporate one or more parts of multiple CXL memory devices with traffic interleaved across them. The user may want to control the scrub rate via this more abstract region instead of having to figure out the constituent devices and program them separately. The scrub rate for each device covers the whole device. Thus if multiple regions use parts of that device then requests for scrubbing of other regions may result in a higher scrub rate than requested for this specific region.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM-hj hhubh)}(hgRegion-based scrubbing is used for the third use case described in "Section 1 CXL Memory Patrol Scrub".h]hkRegion-based scrubbing is used for the third use case described in “Section 1 CXL Memory Patrol Scrub”.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM7hj hhubh)}(hgUserspace must follow below set of rules on how to set the scrub rates for any mixture of requirements.h]hgUserspace must follow below set of rules on how to set the scrub rates for any mixture of requirements.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM:hj hhubj)}(hhh](jw)}(hTaking each region in turn from lowest desired scrub rate to highest and set their scrub rates. Later regions may override the scrub rate on individual devices (and hence potentially whole regions). h]h)}(hTaking each region in turn from lowest desired scrub rate to highest and set their scrub rates. Later regions may override the scrub rate on individual devices (and hence potentially whole regions).h]hTaking each region in turn from lowest desired scrub rate to highest and set their scrub rates. Later regions may override the scrub rate on individual devices (and hence potentially whole regions).}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM=hj ubah}(h]h ]h"]h$]h&]uh1jvhj hhhhhNubjw)}(hXTake each device for which enhanced scrubbing is required (higher rate) and set those scrub rates. This will override the scrub rates of individual devices, setting them to the maximum rate required for any of the regions they help back, unless a specific rate is already defined. h]h)}(hXTake each device for which enhanced scrubbing is required (higher rate) and set those scrub rates. This will override the scrub rates of individual devices, setting them to the maximum rate required for any of the regions they help back, unless a specific rate is already defined.h]hXTake each device for which enhanced scrubbing is required (higher rate) and set those scrub rates. This will override the scrub rates of individual devices, setting them to the maximum rate required for any of the regions they help back, unless a specific rate is already defined.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMAhjubah}(h]h ]h"]h$]h&]uh1jvhj hhhhhNubeh}(h]h ]h"]h$]h&]j>j?j@hjAjBuh1jhj hhhhhM=ubh)}(hXSysfs files for scrubbing are documented in `Documentation/ABI/testing/sysfs-edac-scrub`h](h,Sysfs files for scrubbing are documented in }(hj"hhhNhNubj )}(h,`Documentation/ABI/testing/sysfs-edac-scrub`h]h*Documentation/ABI/testing/sysfs-edac-scrub}(hj*hhhNhNubah}(h]h ]h"]h$]h&]uh1j hj"ubeh}(h]h ]h"]h$]h&]uh1hhhhMFhj hhubj)}(hhh]jw)}(h#CXL memory Error Check Scrub (ECS) h]h)}(h"CXL memory Error Check Scrub (ECS)h]h"CXL memory Error Check Scrub (ECS)}(hjEhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMIhjAubah}(h]h ]h"]h$]h&]uh1jvhj>hhhhhNubah}(h]h ]h"]h$]h&]j>j?j@hjAjBstartKuh1jhj hhhhhMIubh)}(hXThe Error Check Scrub (ECS) feature enables a memory device to perform error checking and correction (ECC) and count single-bit errors. The associated memory controller sets the ECS mode with a trigger sent to the memory device. CXL ECS control allows the host, thus the userspace, to change the attributes for error count mode, threshold number of errors per segment (indicating how many segments have at least that number of errors) for reporting errors, and reset the ECS counter. Thus the responsibility for initiating Error Check Scrub on a memory device may lie with the memory controller or platform when unexpectedly high error rates are detected.h]hXThe Error Check Scrub (ECS) feature enables a memory device to perform error checking and correction (ECC) and count single-bit errors. The associated memory controller sets the ECS mode with a trigger sent to the memory device. CXL ECS control allows the host, thus the userspace, to change the attributes for error count mode, threshold number of errors per segment (indicating how many segments have at least that number of errors) for reporting errors, and reset the ECS counter. 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