diff options
Diffstat (limited to 'arch/riscv/Kconfig')
| -rw-r--r-- | arch/riscv/Kconfig | 58 |
1 files changed, 46 insertions, 12 deletions
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 0bfcfec67ed5..8ebafe337eac 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -704,27 +704,61 @@ config THREAD_SIZE_ORDER affects irq stack size, which is equal to thread stack size. config RISCV_MISALIGNED - bool "Support misaligned load/store traps for kernel and userspace" + bool select SYSCTL_ARCH_UNALIGN_ALLOW - default y help - Say Y here if you want the kernel to embed support for misaligned - load/store for both kernel and userspace. When disable, misaligned - accesses will generate SIGBUS in userspace and panic in kernel. + Embed support for emulating misaligned loads and stores. + +choice + prompt "Unaligned Accesses Support" + default RISCV_PROBE_UNALIGNED_ACCESS + help + This determines the level of support for unaligned accesses. This + information is used by the kernel to perform optimizations. It is also + exposed to user space via the hwprobe syscall. The hardware will be + probed at boot by default. + +config RISCV_PROBE_UNALIGNED_ACCESS + bool "Probe for hardware unaligned access support" + select RISCV_MISALIGNED + help + During boot, the kernel will run a series of tests to determine the + speed of unaligned accesses. This probing will dynamically determine + the speed of unaligned accesses on the underlying system. If unaligned + memory accesses trap into the kernel as they are not supported by the + system, the kernel will emulate the unaligned accesses to preserve the + UABI. + +config RISCV_EMULATED_UNALIGNED_ACCESS + bool "Emulate unaligned access where system support is missing" + select RISCV_MISALIGNED + help + If unaligned memory accesses trap into the kernel as they are not + supported by the system, the kernel will emulate the unaligned + accesses to preserve the UABI. When the underlying system does support + unaligned accesses, the unaligned accesses are assumed to be slow. + +config RISCV_SLOW_UNALIGNED_ACCESS + bool "Assume the system supports slow unaligned memory accesses" + depends on NONPORTABLE + help + Assume that the system supports slow unaligned memory accesses. The + kernel and userspace programs may not be able to run at all on systems + that do not support unaligned memory accesses. config RISCV_EFFICIENT_UNALIGNED_ACCESS - bool "Assume the CPU supports fast unaligned memory accesses" + bool "Assume the system supports fast unaligned memory accesses" depends on NONPORTABLE select DCACHE_WORD_ACCESS if MMU select HAVE_EFFICIENT_UNALIGNED_ACCESS help - Say Y here if you want the kernel to assume that the CPU supports - efficient unaligned memory accesses. When enabled, this option - improves the performance of the kernel on such CPUs. However, the - kernel will run much more slowly, or will not be able to run at all, - on CPUs that do not support efficient unaligned memory accesses. + Assume that the system supports fast unaligned memory accesses. When + enabled, this option improves the performance of the kernel on such + systems. However, the kernel and userspace programs will run much more + slowly, or will not be able to run at all, on systems that do not + support efficient unaligned memory accesses. - If unsure what to do here, say N. +endchoice endmenu # "Platform type" |