Silicon Errata and Software WorkaroundsΒΆ

Author: Will Deacon <will.deacon@arm.com>

Date : 27 November 2015

It is an unfortunate fact of life that hardware is often produced with so-called "errata", which can cause it to deviate from the architecture under specific circumstances. For hardware produced by ARM, these errata are broadly classified into the following categories:

Category A A critical error without a viable workaround.
Category B A significant or critical error with an acceptable workaround.
Category C A minor error that is not expected to occur under normal operation.

For more information, consult one of the "Software Developers Errata Notice" documents available on infocenter.arm.com (registration required).

As far as Linux is concerned, Category B errata may require some special treatment in the operating system. For example, avoiding a particular sequence of code, or configuring the processor in a particular way. A less common situation may require similar actions in order to declassify a Category A erratum into a Category C erratum. These are collectively known as "software workarounds" and are only required in the minority of cases (e.g. those cases that both require a non-secure workaround and can be triggered by Linux).

For software workarounds that may adversely impact systems unaffected by the erratum in question, a Kconfig entry is added under "Kernel Features" -> "ARM errata workarounds via the alternatives framework". These are enabled by default and patched in at runtime when an affected CPU is detected. For less-intrusive workarounds, a Kconfig option is not available and the code is structured (preferably with a comment) in such a way that the erratum will not be hit.

This approach can make it slightly onerous to determine exactly which errata are worked around in an arbitrary kernel source tree, so this file acts as a registry of software workarounds in the Linux Kernel and will be updated when new workarounds are committed and backported to stable kernels.

Implementor Component Erratum ID Kconfig
Allwinner A64/R18 UNKNOWN1 SUN50I_ERRATUM_UNKNOWN1
       
ARM Cortex-A53 #826319 ARM64_ERRATUM_826319
ARM Cortex-A53 #827319 ARM64_ERRATUM_827319
ARM Cortex-A53 #824069 ARM64_ERRATUM_824069
ARM Cortex-A53 #819472 ARM64_ERRATUM_819472
ARM Cortex-A53 #845719 ARM64_ERRATUM_845719
ARM Cortex-A53 #843419 ARM64_ERRATUM_843419
ARM Cortex-A57 #832075 ARM64_ERRATUM_832075
ARM Cortex-A57 #852523 N/A
ARM Cortex-A57 #834220 ARM64_ERRATUM_834220
ARM Cortex-A72 #853709 N/A
ARM Cortex-A73 #858921 ARM64_ERRATUM_858921
ARM Cortex-A55 #1024718 ARM64_ERRATUM_1024718
ARM Cortex-A76 #1188873,1418040 ARM64_ERRATUM_1418040
ARM Cortex-A76 #1165522 ARM64_ERRATUM_1165522
ARM Cortex-A76 #1286807 ARM64_ERRATUM_1286807
ARM Cortex-A76 #1463225 ARM64_ERRATUM_1463225
ARM Neoverse-N1 #1188873,1418040 ARM64_ERRATUM_1418040
ARM Neoverse-N1 #1349291 N/A
ARM MMU-500 #841119,826419 N/A
       
Cavium ThunderX ITS #22375,24313 CAVIUM_ERRATUM_22375
Cavium ThunderX ITS #23144 CAVIUM_ERRATUM_23144
Cavium ThunderX GICv3 #23154 CAVIUM_ERRATUM_23154
Cavium ThunderX Core #27456 CAVIUM_ERRATUM_27456
Cavium ThunderX Core #30115 CAVIUM_ERRATUM_30115
Cavium ThunderX SMMUv2 #27704 N/A
Cavium ThunderX2 SMMUv3 #74 N/A
Cavium ThunderX2 SMMUv3 #126 N/A
Cavium ThunderX2 Core #219 CAVIUM_TX2_ERRATUM_219
       
Freescale/NXP LS2080A/LS1043A A-008585 FSL_ERRATUM_A008585
       
Hisilicon Hip0{5,6,7} #161010101 HISILICON_ERRATUM_161010101
Hisilicon Hip0{6,7} #161010701 N/A
Hisilicon Hip0{6,7} #161010803 N/A
Hisilicon Hip07 #161600802 HISILICON_ERRATUM_161600802
Hisilicon Hip08 SMMU PMCG #162001800 N/A
       
Qualcomm Tech. Kryo/Falkor v1 E1003 QCOM_FALKOR_ERRATUM_1003
Qualcomm Tech. Falkor v1 E1009 QCOM_FALKOR_ERRATUM_1009
Qualcomm Tech. QDF2400 ITS E0065 QCOM_QDF2400_ERRATUM_0065
Qualcomm Tech. Falkor v{1,2} E1041 QCOM_FALKOR_ERRATUM_1041
       
Fujitsu A64FX E#010001 FUJITSU_ERRATUM_010001