CONFIG_NVIDIA_OLYMPUS_1027_ERRATUM: NVIDIA Olympus: device store/load ordering erratum

General informations

The Linux kernel configuration item CONFIG_NVIDIA_OLYMPUS_1027_ERRATUM:

• prompt: NVIDIA Olympus: device store/load ordering erratum
• type: bool
• depends on: (none)
• defined in arch/arm64/Kconfig
• found in Linux kernels: 7.3-rc+HEAD

Help text

This option adds an alternative code sequence to work around an NVIDIA Olympus core erratum where a Device-nGnR* store can be observed by a peripheral after a younger Device-nGnR* load to the same peripheral. This breaks the program order that drivers rely on for MMIO and can leave a device in an incorrect state.

The workaround inserts a DMB OSH immediately before raw MMIO loads. The erratum cannot occur when a DMB that orders loads appears between the store and load, preventing the younger load from being observed before the older store.

The alternatives framework patches in DMB OSH only when an affected CPU is detected. Other CPUs execute a NOP in its place. Disabling this option leaves the original MMIO read instruction stream unchanged.

If unsure, say Y.

Hardware

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Sources

This page is automaticly generated with free (libre, open) software lkddb(see lkddb-sources).

The data is retrived from:

• Linux kernel
• Linux Kernel Driver DataBase (LKDDb)

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