| Silicon Errata and Software Workarounds |
| ======================================= |
| |
| 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 | |
| +----------------+-----------------+-----------------+-----------------------------+ |
| | 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 | 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 | |
| | | | | | |
| | 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 | Hip07 | #161600802 | HISILICON_ERRATUM_161600802 | |
| | | | | | |
| | Qualcomm Tech. | 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 | |
