in their physical address spaces, and this option provides
more efficient handling of these holes. However, the vast
majority of hardware has quite flat address spaces, and
- can have degraded performance from extra overhead that
+ can have degraded performance from the extra overhead that
this option imposes.
Many NUMA configurations will have this as the only option.
config SPARSEMEM
def_bool y
- depends on SPARSEMEM_MANUAL
+ depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL
config FLATMEM
def_bool y
# with gcc 3.4 and later.
#
config SPARSEMEM_STATIC
- def_bool n
+ bool
#
# Architecture platforms which require a two level mem_section in SPARSEMEM
def_bool y
depends on SPARSEMEM && !SPARSEMEM_STATIC
+config SPARSEMEM_VMEMMAP_ENABLE
+ bool
+
+config SPARSEMEM_VMEMMAP
+ bool "Sparse Memory virtual memmap"
+ depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE
+ default y
+ help
+ SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise
+ pfn_to_page and page_to_pfn operations. This is the most
+ efficient option when sufficient kernel resources are available.
+
# eventually, we can have this option just 'select SPARSEMEM'
config MEMORY_HOTPLUG
bool "Allow for memory hot-add"
depends on SPARSEMEM || X86_64_ACPI_NUMA
- depends on HOTPLUG && !SOFTWARE_SUSPEND && ARCH_ENABLE_MEMORY_HOTPLUG
- depends on (IA64 || X86 || PPC64)
-
-comment "Memory hotplug is currently incompatible with Software Suspend"
- depends on SPARSEMEM && HOTPLUG && SOFTWARE_SUSPEND
+ depends on HOTPLUG && ARCH_ENABLE_MEMORY_HOTPLUG
+ depends on (IA64 || X86 || PPC_BOOK3S_64 || SUPERH || S390)
config MEMORY_HOTPLUG_SPARSE
def_bool y
depends on SPARSEMEM && MEMORY_HOTPLUG
+config MEMORY_HOTREMOVE
+ bool "Allow for memory hot remove"
+ depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
+ depends on MIGRATION
+
+#
+# If we have space for more page flags then we can enable additional
+# optimizations and functionality.
+#
+# Regular Sparsemem takes page flag bits for the sectionid if it does not
+# use a virtual memmap. Disable extended page flags for 32 bit platforms
+# that require the use of a sectionid in the page flags.
+#
+config PAGEFLAGS_EXTENDED
+ def_bool y
+ depends on 64BIT || SPARSEMEM_VMEMMAP || !SPARSEMEM
+
# Heavily threaded applications may benefit from splitting the mm-wide
# page_table_lock, so that faults on different parts of the user address
# space can be handled with less contention: split it at this NR_CPUS.
# Default to 4 for wider testing, though 8 might be more appropriate.
# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
+# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
#
config SPLIT_PTLOCK_CPUS
int
- default "4096" if ARM && !CPU_CACHE_VIPT
- default "4096" if PARISC && !PA20
+ default "999999" if ARM && !CPU_CACHE_VIPT
+ default "999999" if PARISC && !PA20
+ default "999999" if DEBUG_SPINLOCK || DEBUG_LOCK_ALLOC
default "4"
#
config MIGRATION
bool "Page migration"
def_bool y
- depends on NUMA
+ depends on NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE
help
Allows the migration of the physical location of pages of processes
while the virtual addresses are not changed. This is useful for
example on NUMA systems to put pages nearer to the processors accessing
the page.
-config RESOURCES_64BIT
- bool "64 bit Memory and IO resources (EXPERIMENTAL)" if (!64BIT && EXPERIMENTAL)
- default 64BIT
- help
- This option allows memory and IO resources to be 64 bit.
+config PHYS_ADDR_T_64BIT
+ def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT
config ZONE_DMA_FLAG
int
default "0" if !ZONE_DMA
default "1"
+config BOUNCE
+ def_bool y
+ depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM)
+
config NR_QUICK
int
depends on QUICKLIST
+ default "2" if SUPERH || AVR32
default "1"
+config VIRT_TO_BUS
+ def_bool y
+ depends on !ARCH_NO_VIRT_TO_BUS
+
+config MMU_NOTIFIER
+ bool
+
+config KSM
+ bool "Enable KSM for page merging"
+ depends on MMU
+ help
+ Enable Kernel Samepage Merging: KSM periodically scans those areas
+ of an application's address space that an app has advised may be
+ mergeable. When it finds pages of identical content, it replaces
+ the many instances by a single page with that content, so
+ saving memory until one or another app needs to modify the content.
+ Recommended for use with KVM, or with other duplicative applications.
+ See Documentation/vm/ksm.txt for more information: KSM is inactive
+ until a program has madvised that an area is MADV_MERGEABLE, and
+ root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).
+
+config DEFAULT_MMAP_MIN_ADDR
+ int "Low address space to protect from user allocation"
+ depends on MMU
+ default 4096
+ help
+ This is the portion of low virtual memory which should be protected
+ from userspace allocation. Keeping a user from writing to low pages
+ can help reduce the impact of kernel NULL pointer bugs.
+
+ For most ia64, ppc64 and x86 users with lots of address space
+ a value of 65536 is reasonable and should cause no problems.
+ On arm and other archs it should not be higher than 32768.
+ Programs which use vm86 functionality or have some need to map
+ this low address space will need CAP_SYS_RAWIO or disable this
+ protection by setting the value to 0.
+
+ This value can be changed after boot using the
+ /proc/sys/vm/mmap_min_addr tunable.
+
+config ARCH_SUPPORTS_MEMORY_FAILURE
+ bool
+
+config MEMORY_FAILURE
+ depends on MMU
+ depends on ARCH_SUPPORTS_MEMORY_FAILURE
+ bool "Enable recovery from hardware memory errors"
+ help
+ Enables code to recover from some memory failures on systems
+ with MCA recovery. This allows a system to continue running
+ even when some of its memory has uncorrected errors. This requires
+ special hardware support and typically ECC memory.
+
+config HWPOISON_INJECT
+ tristate "HWPoison pages injector"
+ depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
+ select PROC_PAGE_MONITOR
+
+config NOMMU_INITIAL_TRIM_EXCESS
+ int "Turn on mmap() excess space trimming before booting"
+ depends on !MMU
+ default 1
+ help
+ The NOMMU mmap() frequently needs to allocate large contiguous chunks
+ of memory on which to store mappings, but it can only ask the system
+ allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
+ more than it requires. To deal with this, mmap() is able to trim off
+ the excess and return it to the allocator.
+
+ If trimming is enabled, the excess is trimmed off and returned to the
+ system allocator, which can cause extra fragmentation, particularly
+ if there are a lot of transient processes.
+
+ If trimming is disabled, the excess is kept, but not used, which for
+ long-term mappings means that the space is wasted.
+
+ Trimming can be dynamically controlled through a sysctl option
+ (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
+ excess pages there must be before trimming should occur, or zero if
+ no trimming is to occur.
+
+ This option specifies the initial value of this option. The default
+ of 1 says that all excess pages should be trimmed.
+
+ See Documentation/nommu-mmap.txt for more information.
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