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Elixir Cross Referencer

# x86 general configuration options

# Copyright (c) 2014-2015 Wind River Systems, Inc.
# SPDX-License-Identifier: Apache-2.0

menu "X86 Architecture Options"
	depends on X86

config ARCH
	default "x86"

#
# CPU Families - the SoC configuration should select the right one.
#

config CPU_ATOM
	bool
	select CPU_HAS_FPU
	select ARCH_HAS_STACK_PROTECTION if X86_MMU
	select ARCH_HAS_USERSPACE if X86_MMU
	help
	  This option signifies the use of a CPU from the Atom family.

config CPU_MINUTEIA
	bool
	select ARCH_HAS_STACK_PROTECTION if X86_MMU
	select ARCH_HAS_USERSPACE if X86_MMU
	help
	  This option signifies the use of a CPU from the Minute IA family.

config CPU_APOLLO_LAKE
	bool
	select CPU_HAS_FPU
	select ARCH_HAS_STACK_PROTECTION if X86_MMU
	select ARCH_HAS_USERSPACE if X86_MMU
	help
	  This option signifies the use of a CPU from the Apollo Lake family.

#
# Configuration common to both IA32 and Intel64 sub-architectures.
#

config X86_64
	bool "Run in 64-bit mode"
	select 64BIT
	select USE_SWITCH
	select USE_SWITCH_SUPPORTED
	select SCHED_IPI_SUPPORTED
	select X86_MMU

config X86_KERNEL_OFFSET
	int "Kernel offset from beginning of RAM"
	default 1048576
	help
	  A lot of x86 that resemble PCs have many reserved physical memory
	  regions within the first megabyte. Specify an offset from the
	  beginning of RAM to load the kernel in physical memory, avoiding these
	  regions.

	  Note that this does not include the "locore" which contains real mode
	  bootstrap code within the first 64K of physical memory.

	  This value normally need to be page-aligned.

config MAX_IRQ_LINES
	int "Number of IRQ lines"
	default 128
	range 0 224
	help
	  This option specifies the number of IRQ lines in the system. It
	  determines the size of the _irq_to_interrupt_vector_table, which
	  is used to track the association between vectors and IRQ numbers.

config IRQ_OFFLOAD_VECTOR
	int "IDT vector to use for IRQ offload"
	default 33
	range 32 255
	depends on IRQ_OFFLOAD

config PIC_DISABLE
	bool "Disable PIC"
	help
	  This option disables all interrupts on the legacy i8259 PICs at boot.

choice
	prompt "Reboot implementation"
	depends on REBOOT
	default REBOOT_RST_CNT

	config REBOOT_RST_CNT
		bool "Reboot via RST_CNT register"
		help
		  Reboot via the RST_CNT register, going back to BIOS.
endchoice

config ACPI
	bool "ACPI (Advanced Configuration and Power Interface) support"
	select ARCH_MAPS_ALL_RAM
	help
	  Allow retrieval of platform configuration at runtime.

config PCIE_MMIO_CFG
	bool "Use MMIO PCI configuration space access"
	select ACPI
	help
	  Selects the use of the memory-mapped PCI Express Extended
	  Configuration Space instead of the traditional 0xCF8/0xCFC
	  IO Port registers.

config KERNEL_VM_SIZE
	default 0xC0000000 if ACPI

config X86_MEMMAP_ENTRIES
	int "Number of memory map entries"
	range 1 256
	default 1 if !MULTIBOOT_MEMMAP
	default 64 if MULTIBOOT_MEMMAP
	help
	  Maximum number of memory regions to hold in the memory map.

config MULTIBOOT
	bool "Generate multiboot header"
	default y
	help
	  Embed a multiboot header in the output executable. This is used
	  by some boot loaders (e.g., GRUB) when loading Zephyr. It is safe
	  to leave this option on if you're not sure. It only expands the
	  text segment by 12-16 bytes and is typically ignored if not needed.

if MULTIBOOT

config MULTIBOOT_INFO
	bool "Preserve multiboot information structure"
	help
	  Multiboot passes a pointer to an information structure to the
	  kernel entry point. Some drivers (e.g., the multiboot framebuffer
	  display driver) need to refer to information in this structure,
	  and so set this option to preserve the data in a permanent location.

config MULTIBOOT_MEMMAP
	bool "Use multiboot memory map if provided"
	select MULTIBOOT_INFO
	help
	  Use the multiboot memory map if the loader provides one.

config MULTIBOOT_FRAMEBUF
	bool "Multiboot framebuffer support"
	select DISPLAY
	select FRAMEBUF_DISPLAY
	select MULTIBOOT_INFO

if MULTIBOOT_FRAMEBUF

config MULTIBOOT_FRAMEBUF_X
	int "Multiboot framebuffer X pixels"
	default 640

config MULTIBOOT_FRAMEBUF_Y
	int "Multiboot framebuffer Y pixels"
	default 480

endif # MULTIBOOT_FRAMEBUF

endif # MULTIBOOT

config EXCEPTION_DEBUG
	bool "Unhandled exception debugging"
	default y
	depends on LOG
	help
	  Install handlers for various CPU exception/trap vectors to
	  make debugging them easier, at a small expense in code size.
	  This prints out the specific exception vector and any associated
	  error codes.

config X86_VERY_EARLY_CONSOLE
	bool "Support very early boot printk"
	depends on PRINTK
	default y
	help
	  Non-emulated X86 devices often require special hardware to attach
	  a debugger, which may not be easily available. This option adds a
	  very minimal serial driver which gets initialized at the very
	  beginning of z_cstart(), via arch_kernel_init(). This driver enables
	  printk to emit messages to the 16550 UART port 0 instance in device
	  tree. This mini-driver assumes I/O to the UART is done via ports.

config X86_MMU
	bool "Enable Memory Management Unit"
	select MMU
	help
	  This options enables the memory management unit present in x86
	  and creates a set of page tables at boot time that is runtime-
	  mutable.

config X86_COMMON_PAGE_TABLE
	bool "Use a single page table for all threads"
	default n
	depends on USERSPACE
	depends on !SMP
	depends on !X86_KPTI
	help
	  If this option is enabled, userspace memory domains will not have their
	  own page tables. Instead, context switching operations will modify
	  page tables in place. This is much slower, but uses much less RAM
	  for page tables.

config X86_MAX_ADDITIONAL_MEM_DOMAINS
	int "Maximum number of memory domains"
	default 3
	depends on X86_MMU && USERSPACE && !X86_COMMON_PAGE_TABLE
	help
	  The initial page tables at boot are pre-allocated, and used for the
	  default memory domain. Instantiation of additional memory domains
	  if common page tables are in use requires a pool of free pinned
	  memory pages for constructing page tables.

	  Zephyr test cases assume 3 additional domains can be instantiated.

config X86_NO_MELTDOWN
	bool
	help
	  This hidden option should be set on a per-SOC basis to indicate that
	  a particular SOC is not vulnerable to the Meltdown CPU vulnerability,
	  as described in CVE-2017-5754.

config X86_NO_SPECTRE_V1
	bool
	help
	  This hidden option should be set on a per-SOC basis to indicate that
	  a particular SOC is not vulnerable to the Spectre V1, V1.1, V1.2, and
	  swapgs CPU vulnerabilities as described in CVE-2017-5753,
	  CVE-2018-3693, and CVE-2019-1125.

config X86_NO_SPECTRE_V2
	bool
	help
	  This hidden option should be set on a per-SOC basis to indicate that
	  a particular SOC is not vulnerable to the Spectre V2 CPU
	  vulnerability, as described in CVE-2017-5715.

config X86_NO_SPECTRE_V4
	bool
	help
	  This hidden option should be set on a per-SOC basis to indicate that
	  a particular SOC is not vulnerable to the Spectre V4 CPU
	  vulnerability, as described in CVE-2018-3639.

config X86_NO_LAZY_FP
	bool
	help
	  This hidden option should be set on a per-SOC basis to indicate
	  that a particular SOC is not vulnerable to the Lazy FP CPU
	  vulnerability, as described in CVE-2018-3665.

config X86_NO_SPECULATIVE_VULNERABILITIES
	bool
	select X86_NO_MELTDOWN
	select X86_NO_SPECTRE_V1
	select X86_NO_SPECTRE_V2
	select X86_NO_SPECTRE_V4
	select X86_NO_LAZY_FP
	help
	  This hidden option should be set on a per-SOC basis to indicate that
	  a particular SOC does not perform any kind of speculative execution,
	  or is a newer chip which is immune to the class of vulnerabilities
	  which exploit speculative execution side channel attacks.

config DISABLE_SSBD
	bool "Disable Speculative Store Bypass"
	depends on USERSPACE
	default y if !X86_NO_SPECTRE_V4
	help
	  This option will disable Speculative Store Bypass in order to
	  mitigate against certain kinds of side channel attacks.  Quoting
	  the "Speculative Execution Side Channels" document, version 2.0:

	      When SSBD is set, loads will not execute speculatively
	      until the addresses of all older stores are known.  This
	      ensure s that a load does not speculatively consume stale
	      data values due to bypassing an older store on the same
	      logical processor.

	  If enabled, this applies to all threads in the system.

	  Even if enabled, will have no effect on CPUs that do not
	  require this feature.

config ENABLE_EXTENDED_IBRS
	bool "Enable Extended IBRS"
	depends on USERSPACE
	default y if !X86_NO_SPECTRE_V2
	help
	  This option will enable the Extended Indirect Branch Restricted
	  Speculation 'always on' feature. This mitigates Indirect Branch
	  Control vulnerabilities (aka Spectre V2).

config X86_BOUNDS_CHECK_BYPASS_MITIGATION
	bool
	depends on USERSPACE
	default y if !X86_NO_SPECTRE_V1
	select BOUNDS_CHECK_BYPASS_MITIGATION
	help
	  Hidden config to select arch-independent option to enable
	  Spectre V1 mitigations by default if the CPU is not known
	  to be immune to it.

config X86_KPTI
	bool "Enable kernel page table isolation"
	default y
	depends on USERSPACE
	depends on !X86_NO_MELTDOWN
	help
	  Implements kernel page table isolation to mitigate Meltdown exploits
	  to read Kernel RAM. Incurs a significant performance cost for
	  user thread interrupts and system calls, and significant footprint
	  increase for additional page tables and trampoline stacks.

source "arch/x86/core/Kconfig.ia32"
source "arch/x86/core/Kconfig.intel64"

endmenu