Current File : //usr/src/linux-headers-5.15.0-125-generic/arch/sh/mm/Kconfig
# SPDX-License-Identifier: GPL-2.0
menu "Memory management options"
config MMU
bool "Support for memory management hardware"
depends on !CPU_SH2
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 PAGE_OFFSET
hex
default "0x80000000" if MMU
default "0x00000000"
config FORCE_MAX_ZONEORDER
int "Maximum zone order"
range 9 64 if PAGE_SIZE_16KB
default "9" if PAGE_SIZE_16KB
range 7 64 if PAGE_SIZE_64KB
default "7" if PAGE_SIZE_64KB
range 11 64
default "14" if !MMU
default "11"
help
The kernel memory allocator divides physically contiguous memory
blocks into "zones", where each zone is a power of two number of
pages. This option selects the largest power of two that the kernel
keeps in the memory allocator. If you need to allocate very large
blocks of physically contiguous memory, then you may need to
increase this value.
This config option is actually maximum order plus one. For example,
a value of 11 means that the largest free memory block is 2^10 pages.
The page size is not necessarily 4KB. Keep this in mind when
choosing a value for this option.
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"
help
This sets the default memory size assumed by your SH kernel. It can
be overridden as normal by the 'mem=' argument on the kernel command
line. If unsure, consult your board specifications or just leave it
as 0x04000000 which was the default value before this became
configurable.
# Physical addressing modes
config 29BIT
def_bool !32BIT
select UNCACHED_MAPPING
config 32BIT
bool
default !MMU
config PMB
bool "Support 32-bit physical addressing through PMB"
depends on MMU && CPU_SH4A && !CPU_SH4AL_DSP
select 32BIT
select UNCACHED_MAPPING
help
If you say Y here, physical addressing will be extended to
32-bits through the SH-4A PMB. If this is not set, legacy
29-bit physical addressing will be used.
config X2TLB
def_bool y
depends on (CPU_SHX2 || CPU_SHX3) && MMU
config VSYSCALL
bool "Support vsyscall page"
depends on MMU && (CPU_SH3 || CPU_SH4)
default y
help
This will enable support for the kernel mapping a vDSO page
in process space, and subsequently handing down the entry point
to the libc through the ELF auxiliary vector.
From the kernel side this is used for the signal trampoline.
For systems with an MMU that can afford to give up a page,
(the default value) say Y.
config NUMA
bool "Non-Uniform Memory Access (NUMA) Support"
depends on MMU && SYS_SUPPORTS_NUMA
select ARCH_WANT_NUMA_VARIABLE_LOCALITY
default n
help
Some SH systems have many various memories scattered around
the address space, each with varying latencies. This enables
support for these blocks by binding them to nodes and allowing
memory policies to be used for prioritizing and controlling
allocation behaviour.
config NODES_SHIFT
int
default "3" if CPU_SUBTYPE_SHX3
default "1"
depends on NUMA
config ARCH_FLATMEM_ENABLE
def_bool y
depends on !NUMA
config ARCH_SPARSEMEM_ENABLE
def_bool y
select SPARSEMEM_STATIC
config ARCH_SPARSEMEM_DEFAULT
def_bool y
config ARCH_SELECT_MEMORY_MODEL
def_bool y
config ARCH_MEMORY_PROBE
def_bool y
depends on MEMORY_HOTPLUG
config IOREMAP_FIXED
def_bool y
depends on X2TLB
config UNCACHED_MAPPING
bool
config HAVE_SRAM_POOL
bool
select GENERIC_ALLOCATOR
choice
prompt "Kernel page size"
default PAGE_SIZE_4KB
config PAGE_SIZE_4KB
bool "4kB"
help
This is the default page size used by all SuperH CPUs.
config PAGE_SIZE_8KB
bool "8kB"
depends on !MMU || X2TLB
help
This enables 8kB pages as supported by SH-X2 and later MMUs.
config PAGE_SIZE_16KB
bool "16kB"
depends on !MMU
help
This enables 16kB pages on MMU-less SH systems.
config PAGE_SIZE_64KB
bool "64kB"
depends on !MMU || CPU_SH4
help
This enables support for 64kB pages, possible on all SH-4
CPUs and later.
endchoice
choice
prompt "HugeTLB page size"
depends on HUGETLB_PAGE
default HUGETLB_PAGE_SIZE_1MB if PAGE_SIZE_64KB
default HUGETLB_PAGE_SIZE_64K
config HUGETLB_PAGE_SIZE_64K
bool "64kB"
depends on !PAGE_SIZE_64KB
config HUGETLB_PAGE_SIZE_256K
bool "256kB"
depends on X2TLB
config HUGETLB_PAGE_SIZE_1MB
bool "1MB"
config HUGETLB_PAGE_SIZE_4MB
bool "4MB"
depends on X2TLB
config HUGETLB_PAGE_SIZE_64MB
bool "64MB"
depends on X2TLB
endchoice
config SCHED_MC
bool "Multi-core scheduler support"
depends on SMP
default y
help
Multi-core scheduler support improves the CPU scheduler's decision
making when dealing with multi-core CPU chips at a cost of slightly
increased overhead in some places. If unsure say N here.
endmenu
menu "Cache configuration"
config SH7705_CACHE_32KB
bool "Enable 32KB cache size for SH7705"
depends on CPU_SUBTYPE_SH7705
default y
choice
prompt "Cache mode"
default CACHE_WRITEBACK if CPU_SH2A || CPU_SH3 || CPU_SH4
default CACHE_WRITETHROUGH if (CPU_SH2 && !CPU_SH2A)
config CACHE_WRITEBACK
bool "Write-back"
config CACHE_WRITETHROUGH
bool "Write-through"
help
Selecting this option will configure the caches in write-through
mode, as opposed to the default write-back configuration.
Since there's sill some aliasing issues on SH-4, this option will
unfortunately still require the majority of flushing functions to
be implemented to deal with aliasing.
If unsure, say N.
config CACHE_OFF
bool "Off"
endchoice
endmenu
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