# Kconfig - x86 general configuration options # # Copyright (c) 2014-2015 Wind River Systems, Inc. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. # choice prompt "x86 SoC Selection" depends on X86 source "arch/x86/soc/*/Kconfig.soc" endchoice menu "x86 Options" depends on X86 config ARCH default "x86" config ARCH_DEFCONFIG string default "arch/x86/defconfig" source "arch/x86/core/Kconfig" # # Hidden CPU family configs which are to be selected by # individual SoC. # config CPU_ATOM # Hidden bool select CMOV select CPU_HAS_FPU help This option signifies the use of a CPU from the Atom family. config CPU_MINUTEIA # Hidden bool help This option signifies the use of a CPU from the Minute IA family. # # End hidden CPU family configs # config CPU_HAS_FPU # Hidden config selected by CPU family bool default n help This option is enabled when the CPU has hardware floating point unit. menu "Processor Capabilities" config X86_IAMCU bool default n prompt "IAMCU calling convention" help The IAMCU calling convention changes the X86 C calling convention to pass some arguments via registers allowing for code size and performance improvements. Great care needs to be taken if you have assembly code that will be called from C or C code called from assembly code, the assembly code will need to be updated to conform to the new calling convention. If in doubt say N menu "Floating Point Options" depends on CPU_HAS_FPU config FLOAT bool prompt "Floating point registers" default n help This option allows threads to use the x87 FPU/MMX registers. The registers may be used by any number of cooperative threads or by a single preemptible thread, but not both, since the kernel does not preserve FPU context information when switching between threads. Additional options must be enabled to permit the use of SSE registers or to permit floating point register use by multiple preemptible threads. Disabling this option means that any thread that uses the floating point registers will get a fatal exception. config FP_SHARING bool prompt "Floating point register sharing" depends on FLOAT default n help This option allows multiple preemptible threads to use the floating point registers. Any preemptible thread that uses the registers must provide stack space where the kernel can save FPU context info during a preemptive context switch. A thread that uses only the x87 FPU/MMX registers must provide 108 bytes of added stack space, while a thread the uses the SSE registers must provide 464 bytes of added stack space. config SSE bool prompt "SSE registers" depends on FLOAT default n help This option enables the use of SSE registers by threads. config SSE_FP_MATH bool prompt "Compiler-generated SSEx instructions" depends on SSE default n help This option allows the compiler to generate SSEx instructions for performing floating point math. This can greatly improve performance when exactly the same operations are to be performed on multiple data objects; however, it can also significantly reduce performance when pre-emptive task switches occur because of the larger register set that must be saved and restored. Disabling this option means that the compiler utilizes only the x87 instruction set for floating point operations. endmenu choice prompt "Reboot implementation" depends on REBOOT default REBOOT_RST_CNT config REBOOT_RST_CNT bool prompt "Reboot via RST_CNT register" help Reboot via the RST_CNT register, going back to BIOS. endchoice config ISA_IA32 bool default y help This option signifies the use of a CPU based on the Intel IA-32 instruction set architecture. config IA32_LEGACY_IO_PORTS bool prompt "Support IA32 legacy IO ports" default n depends on ISA_IA32 help This option enables IA32 legacy IO ports. Note these are much slower than memory access, so they should be used in last resort. config CMOV def_bool n help This option signifies the use of an Intel CPU that supports the CMOV instruction. config CACHE_LINE_SIZE_DETECT bool prompt "Detect cache line size at runtime" default y help This option enables querying the CPUID register for finding the cache line size at the expense of taking more memory and code and a slightly increased boot time. If the CPU's cache line size is known in advance, disable this option and manually enter the value for CACHE_LINE_SIZE. config CACHE_LINE_SIZE int prompt "Cache line size" if !CACHE_LINE_SIZE_DETECT default 0 if CACHE_LINE_SIZE_DETECT default 64 if CPU_ATOM default 0 help Size in bytes of a CPU cache line. Detect automatically at runtime by selecting CACHE_LINE_SIZE_DETECT. config CLFLUSH_INSTRUCTION_SUPPORTED bool prompt "CLFLUSH instruction supported" depends on !CLFLUSH_DETECT && CACHE_FLUSHING default n help An implementation of sys_cache_flush() that uses CLFLUSH is made available, instead of the one using WBINVD. This option should only be enabled if it is known in advance that the CPU supports the CLFLUSH instruction. It disables runtime detection of CLFLUSH support thereby reducing both memory footprint and boot time. config CLFLUSH_DETECT bool prompt "Detect support of CLFLUSH instruction at runtime" depends on CACHE_FLUSHING default n help This option should be enabled if it is not known in advance whether the CPU supports the CLFLUSH instruction or not. The CPU is queried at boot time to determine which of the multiple implementations of sys_cache_flush() linked into the image is the correct one to use. If the CPU's support (or lack thereof) of CLFLUSH is known in advance, then disable this option and set CLFLUSH_INSTRUCTION_SUPPORTED as appropriate. config ARCH_CACHE_FLUSH_DETECT bool default y depends on CLFLUSH_DETECT config CACHE_FLUSHING bool default n prompt "Enable cache flushing mechanism" help This links in the sys_cache_flush() function. A mechanism for flushing the cache must be selected as well. By default, that mechanism is discovered at runtime. endmenu menu "Board Capabilities" config PIC_DISABLE bool "Disable PIC" default n help This option disables all interrupts on the PIC config IRQ_OFFLOAD bool "Enable IRQ offload" default n help Enable irq_offload() API which allows functions to be synchronously run in interrupt context. Uses one entry in the IDT. Mainly useful for test cases. config IRQ_OFFLOAD_VECTOR int "IDT vector to use for IRQ offload" default 63 if MVIC default 32 if !MVIC range 32 255 depends on IRQ_OFFLOAD help Specify the IDT vector to use for the IRQ offload interrupt handler. The default should be fine for most arches, but on systems like MVIC where there is a fixed IRQ-to-vector mapping another value may be needed to avoid collision. config XIP default n config X86_FIXED_IRQ_MAPPING bool default n help Specify whether the current interrupt controller in use has a fixed mapping between IDT vectors and IRQ lines. endmenu source "arch/x86/soc/*/Kconfig" endmenu