arch/sh/mm/Kconfig

Source file repositories/reference/linux-study-clean/arch/sh/mm/Kconfig

File Facts

System
Linux kernel
Corpus path
arch/sh/mm/Kconfig
Extension
[no extension]
Size
5894 bytes
Lines
229
Domain
Architecture Layer
Bucket
arch/sh
Inferred role
Architecture Layer: build/configuration rule
Status
atlas-only

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

# SPDX-License-Identifier: GPL-2.0
menu "Memory management options"

config MMU
        bool "Support for memory management hardware"
	depends on !CPU_SH2
	select HAVE_PAGE_SIZE_4KB
	select HAVE_PAGE_SIZE_8KB if X2TLB
	select HAVE_PAGE_SIZE_64KB if CPU_SH4
	default y
	help
	  Some SH processors (such as SH-2/SH-2A) lack an MMU. In order to
	  boot on these systems, this option must not be set.

	  On other systems (such as the SH-3 and 4) where an MMU exists,
	  turning this off will boot the kernel on these machines with the
	  MMU implicitly switched off.

config NOMMU
	def_bool !MMU
	select HAVE_PAGE_SIZE_4KB
	select HAVE_PAGE_SIZE_8KB
	select HAVE_PAGE_SIZE_16KB
	select HAVE_PAGE_SIZE_64KB
	help
	  On MMU-less systems, any of these page sizes can be selected

config PAGE_OFFSET
	hex
	default "0x80000000" if MMU
	default "0x00000000"

config ARCH_FORCE_MAX_ORDER
	int "Order of maximal physically contiguous allocations"
	default "8" if PAGE_SIZE_16KB
	default "6" if PAGE_SIZE_64KB
	default "13" if !MMU
	default "10"
	help
	  The kernel page allocator limits the size of maximal physically
	  contiguous allocations. The limit is called MAX_PAGE:_ORDER and it
	  defines the maximal power of two of number of pages that can be
	  allocated as a single contiguous block. This option allows
	  overriding the default setting when ability to allocate very
	  large blocks of physically contiguous memory is required.

	  The page size is not necessarily 4KB. Keep this in mind when
	  choosing a value for this option.

	  Don't change if unsure.

config MEMORY_START
	hex "Physical memory start address"
	default "0x08000000"
	help
	  Computers built with Hitachi SuperH processors always
	  map the ROM starting at address zero.  But the processor
	  does not specify the range that RAM takes.

	  The physical memory (RAM) start address will be automatically
	  set to 08000000. Other platforms, such as the Solution Engine
	  boards typically map RAM at 0C000000.

	  Tweak this only when porting to a new machine which does not
	  already have a defconfig. Changing it from the known correct
	  value on any of the known systems will only lead to disaster.

config MEMORY_SIZE
	hex "Physical memory size"
	default "0x04000000"

Annotation

Implementation Notes