CONFIG_RISCV_SBI_FWFT_DELEGATE_MISALIGNED: Request firmware delegation of unaligned access exceptions

General informations

The Linux kernel configuration item CONFIG_RISCV_SBI_FWFT_DELEGATE_MISALIGNED:

• prompt: Request firmware delegation of unaligned access exceptions
• type: bool
• depends on: ( CONFIG_RISCV_SBI ) && ( CONFIG_NONPORTABLE )
• defined in arch/riscv/Kconfig
• found in Linux kernels: 7.1-rc+HEAD

Help text

Use SBI FWFT to request delegation of load address misaligned and store address misaligned exceptions, if possible, and prefer Linux kernel emulation of these accesses to firmware emulation.

Unfortunately, Linux's emulation is still incomplete. Namely, it currently does not handle vector instructions and KVM guest accesses. On platforms where these accesses would have been handled by firmware, enabling this causes unexpected kernel oopses, userspaces crashes and KVM guest crashes. If you are sure that these are not a problem for your platform, you can say Y here, which may improve performance.

Saying N here will not worsen emulation support for unaligned accesses even in the case where the firmware also has incomplete support. It simply keeps the firmware's emulation enabled.

If you don't know what to do here, say N.

Hardware

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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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