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| 1 | +What: /sys/bus/edac/devices/<dev-name>/mem_repairX |
| 2 | +Date: March 2025 |
| 3 | +KernelVersion: 6.15 |
| 4 | +Contact: linux-edac@vger.kernel.org |
| 5 | +Description: |
| 6 | + The sysfs EDAC bus devices /<dev-name>/mem_repairX subdirectory |
| 7 | + pertains to the memory media repair features control, such as |
| 8 | + PPR (Post Package Repair), memory sparing etc, where <dev-name> |
| 9 | + directory corresponds to a device registered with the EDAC |
| 10 | + device driver for the memory repair features. |
| 11 | + |
| 12 | + Post Package Repair is a maintenance operation requests the memory |
| 13 | + device to perform a repair operation on its media. It is a memory |
| 14 | + self-healing feature that fixes a failing memory location by |
| 15 | + replacing it with a spare row in a DRAM device. For example, a |
| 16 | + CXL memory device with DRAM components that support PPR features may |
| 17 | + implement PPR maintenance operations. DRAM components may support |
| 18 | + two types of PPR functions: hard PPR, for a permanent row repair, and |
| 19 | + soft PPR, for a temporary row repair. Soft PPR may be much faster |
| 20 | + than hard PPR, but the repair is lost with a power cycle. |
| 21 | + |
| 22 | + The sysfs attributes nodes for a repair feature are only |
| 23 | + present if the parent driver has implemented the corresponding |
| 24 | + attr callback function and provided the necessary operations |
| 25 | + to the EDAC device driver during registration. |
| 26 | + |
| 27 | + In some states of system configuration (e.g. before address |
| 28 | + decoders have been configured), memory devices (e.g. CXL) |
| 29 | + may not have an active mapping in the main host address |
| 30 | + physical address map. As such, the memory to repair must be |
| 31 | + identified by a device specific physical addressing scheme |
| 32 | + using a device physical address(DPA). The DPA and other control |
| 33 | + attributes to use will be presented in related error records. |
| 34 | + |
| 35 | +What: /sys/bus/edac/devices/<dev-name>/mem_repairX/repair_type |
| 36 | +Date: March 2025 |
| 37 | +KernelVersion: 6.15 |
| 38 | +Contact: linux-edac@vger.kernel.org |
| 39 | +Description: |
| 40 | + (RO) Memory repair type. For eg. post package repair, |
| 41 | + memory sparing etc. Valid values are: |
| 42 | + |
| 43 | + - ppr - Post package repair. |
| 44 | + |
| 45 | + - cacheline-sparing |
| 46 | + |
| 47 | + - row-sparing |
| 48 | + |
| 49 | + - bank-sparing |
| 50 | + |
| 51 | + - rank-sparing |
| 52 | + |
| 53 | + - All other values are reserved. |
| 54 | + |
| 55 | +What: /sys/bus/edac/devices/<dev-name>/mem_repairX/persist_mode |
| 56 | +Date: March 2025 |
| 57 | +KernelVersion: 6.15 |
| 58 | +Contact: linux-edac@vger.kernel.org |
| 59 | +Description: |
| 60 | + (RW) Get/Set the current persist repair mode set for a |
| 61 | + repair function. Persist repair modes supported in the |
| 62 | + device, based on a memory repair function, either is temporary, |
| 63 | + which is lost with a power cycle or permanent. Valid values are: |
| 64 | + |
| 65 | + - 0 - Soft memory repair (temporary repair). |
| 66 | + |
| 67 | + - 1 - Hard memory repair (permanent repair). |
| 68 | + |
| 69 | + - All other values are reserved. |
| 70 | + |
| 71 | +What: /sys/bus/edac/devices/<dev-name>/mem_repairX/repair_safe_when_in_use |
| 72 | +Date: March 2025 |
| 73 | +KernelVersion: 6.15 |
| 74 | +Contact: linux-edac@vger.kernel.org |
| 75 | +Description: |
| 76 | + (RO) True if memory media is accessible and data is retained |
| 77 | + during the memory repair operation. |
| 78 | + The data may not be retained and memory requests may not be |
| 79 | + correctly processed during a repair operation. In such case |
| 80 | + repair operation can not be executed at runtime. The memory |
| 81 | + must be taken offline. |
| 82 | + |
| 83 | +What: /sys/bus/edac/devices/<dev-name>/mem_repairX/hpa |
| 84 | +Date: March 2025 |
| 85 | +KernelVersion: 6.15 |
| 86 | +Contact: linux-edac@vger.kernel.org |
| 87 | +Description: |
| 88 | + (RW) Host Physical Address (HPA) of the memory to repair. |
| 89 | + The HPA to use will be provided in related error records. |
| 90 | + |
| 91 | +What: /sys/bus/edac/devices/<dev-name>/mem_repairX/dpa |
| 92 | +Date: March 2025 |
| 93 | +KernelVersion: 6.15 |
| 94 | +Contact: linux-edac@vger.kernel.org |
| 95 | +Description: |
| 96 | + (RW) Device Physical Address (DPA) of the memory to repair. |
| 97 | + The specific DPA to use will be provided in related error |
| 98 | + records. |
| 99 | + |
| 100 | + In some states of system configuration (e.g. before address |
| 101 | + decoders have been configured), memory devices (e.g. CXL) |
| 102 | + may not have an active mapping in the main host address |
| 103 | + physical address map. As such, the memory to repair must be |
| 104 | + identified by a device specific physical addressing scheme |
| 105 | + using a DPA. The device physical address(DPA) to use will be |
| 106 | + presented in related error records. |
| 107 | + |
| 108 | +What: /sys/bus/edac/devices/<dev-name>/mem_repairX/nibble_mask |
| 109 | +Date: March 2025 |
| 110 | +KernelVersion: 6.15 |
| 111 | +Contact: linux-edac@vger.kernel.org |
| 112 | +Description: |
| 113 | + (RW) Read/Write Nibble mask of the memory to repair. |
| 114 | + Nibble mask identifies one or more nibbles in error on the |
| 115 | + memory bus that produced the error event. Nibble Mask bit 0 |
| 116 | + shall be set if nibble 0 on the memory bus produced the |
| 117 | + event, etc. For example, CXL PPR and sparing, a nibble mask |
| 118 | + bit set to 1 indicates the request to perform repair |
| 119 | + operation in the specific device. All nibble mask bits set |
| 120 | + to 1 indicates the request to perform the operation in all |
| 121 | + devices. Eg. for CXL memory repair, the specific value of |
| 122 | + nibble mask to use will be provided in related error records. |
| 123 | + For more details, See nibble mask field in CXL spec ver 3.1, |
| 124 | + section 8.2.9.7.1.2 Table 8-103 soft PPR and section |
| 125 | + 8.2.9.7.1.3 Table 8-104 hard PPR, section 8.2.9.7.1.4 |
| 126 | + Table 8-105 memory sparing. |
| 127 | + |
| 128 | +What: /sys/bus/edac/devices/<dev-name>/mem_repairX/min_hpa |
| 129 | +What: /sys/bus/edac/devices/<dev-name>/mem_repairX/max_hpa |
| 130 | +What: /sys/bus/edac/devices/<dev-name>/mem_repairX/min_dpa |
| 131 | +What: /sys/bus/edac/devices/<dev-name>/mem_repairX/max_dpa |
| 132 | +Date: March 2025 |
| 133 | +KernelVersion: 6.15 |
| 134 | +Contact: linux-edac@vger.kernel.org |
| 135 | +Description: |
| 136 | + (RW) The supported range of memory address that is to be |
| 137 | + repaired. The memory device may give the supported range of |
| 138 | + attributes to use and it will depend on the memory device |
| 139 | + and the portion of memory to repair. |
| 140 | + The userspace may receive the specific value of attributes |
| 141 | + to use for a repair operation from the memory device via |
| 142 | + related error records and trace events, for eg. CXL DRAM |
| 143 | + and CXL general media error records in CXL memory devices. |
| 144 | + |
| 145 | +What: /sys/bus/edac/devices/<dev-name>/mem_repairX/bank_group |
| 146 | +What: /sys/bus/edac/devices/<dev-name>/mem_repairX/bank |
| 147 | +What: /sys/bus/edac/devices/<dev-name>/mem_repairX/rank |
| 148 | +What: /sys/bus/edac/devices/<dev-name>/mem_repairX/row |
| 149 | +What: /sys/bus/edac/devices/<dev-name>/mem_repairX/column |
| 150 | +What: /sys/bus/edac/devices/<dev-name>/mem_repairX/channel |
| 151 | +What: /sys/bus/edac/devices/<dev-name>/mem_repairX/sub_channel |
| 152 | +Date: March 2025 |
| 153 | +KernelVersion: 6.15 |
| 154 | +Contact: linux-edac@vger.kernel.org |
| 155 | +Description: |
| 156 | + (RW) The control attributes for the memory to be repaired. |
| 157 | + The specific value of attributes to use depends on the |
| 158 | + portion of memory to repair and will be reported to the host |
| 159 | + in related error records and be available to userspace |
| 160 | + in trace events, such as CXL DRAM and CXL general media |
| 161 | + error records of CXL memory devices. |
| 162 | + |
| 163 | + When readng back these attributes, it returns the current |
| 164 | + value of memory requested to be repaired. |
| 165 | + |
| 166 | + bank_group - The bank group of the memory to repair. |
| 167 | + |
| 168 | + bank - The bank number of the memory to repair. |
| 169 | + |
| 170 | + rank - The rank of the memory to repair. Rank is defined as a |
| 171 | + set of memory devices on a channel that together execute a |
| 172 | + transaction. |
| 173 | + |
| 174 | + row - The row number of the memory to repair. |
| 175 | + |
| 176 | + column - The column number of the memory to repair. |
| 177 | + |
| 178 | + channel - The channel of the memory to repair. Channel is |
| 179 | + defined as an interface that can be independently accessed |
| 180 | + for a transaction. |
| 181 | + |
| 182 | + sub_channel - The subchannel of the memory to repair. |
| 183 | + |
| 184 | + The requirement to set these attributes varies based on the |
| 185 | + repair function. The attributes in sysfs are not present |
| 186 | + unless required for a repair function. |
| 187 | + |
| 188 | + For example, CXL spec ver 3.1, Section 8.2.9.7.1.2 Table 8-103 |
| 189 | + soft PPR and Section 8.2.9.7.1.3 Table 8-104 hard PPR operations, |
| 190 | + these attributes are not required to set. CXL spec ver 3.1, |
| 191 | + Section 8.2.9.7.1.4 Table 8-105 memory sparing, these attributes |
| 192 | + are required to set based on memory sparing granularity. |
| 193 | + |
| 194 | +What: /sys/bus/edac/devices/<dev-name>/mem_repairX/repair |
| 195 | +Date: March 2025 |
| 196 | +KernelVersion: 6.15 |
| 197 | +Contact: linux-edac@vger.kernel.org |
| 198 | +Description: |
| 199 | + (WO) Issue the memory repair operation for the specified |
| 200 | + memory repair attributes. The operation may fail if resources |
| 201 | + are insufficient based on the requirements of the memory |
| 202 | + device and repair function. |
| 203 | + |
| 204 | + - 1 - Issue the repair operation. |
| 205 | + |
| 206 | + - All other values are reserved. |
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