:orphan:

.. title:: CONFIG_DEMAND_PAGING_PAGE_FRAMES_RESERVE

.. kconfig:: CONFIG_DEMAND_PAGING_PAGE_FRAMES_RESERVE

CONFIG_DEMAND_PAGING_PAGE_FRAMES_RESERVE
########################################

*Number of page frames reserved for paging*

Type: ``int``

Help
====

.. code-block:: none

    This sets the number of page frames that will be reserved for
    paging that do not count towards free memory. This is to
    ensure that there are some page frames available for paging
    code and data. Otherwise, it would be possible to exhaust
    all page frames via anonymous memory mappings.

Direct dependencies
===================

\ :kconfig:`BOARD_QEMU_X86_TINY <CONFIG_BOARD_QEMU_X86_TINY>` || (\ :kconfig:`DEMAND_PAGING <CONFIG_DEMAND_PAGING>` && \ :kconfig:`MMU <CONFIG_MMU>`)

*(Includes any dependencies from ifs and menus.)*

Defaults
========

- 6 if \ :kconfig:`NEWLIB_LIBC <CONFIG_NEWLIB_LIBC>`
- 32 if !\ :kconfig:`LINKER_GENERIC_SECTIONS_PRESENT_AT_BOOT <CONFIG_LINKER_GENERIC_SECTIONS_PRESENT_AT_BOOT>`
- 0

Kconfig definitions
===================



At ``<Boards>/x86/qemu_x86/Kconfig.defconfig:107``

Included via ``Kconfig:8`` → ``Kconfig.zephyr:22``

Menu path: (Top)

.. code-block:: kconfig

    config DEMAND_PAGING_PAGE_FRAMES_RESERVE
    	int
    	default 6 if NEWLIB_LIBC
    	depends on BOARD_QEMU_X86_TINY

----

At ``<Kernel>/Kconfig.vm:125``

Included via ``Kconfig:8`` → ``Kconfig.zephyr:40`` → ``<Kernel>/Kconfig:923``

Menu path: (Top) → Virtual Memory Support → Enable MMU features → Enable demand paging [EXPERIMENTAL]

.. code-block:: kconfig

    config DEMAND_PAGING_PAGE_FRAMES_RESERVE
    	int "Number of page frames reserved for paging"
    	default 32 if !LINKER_GENERIC_SECTIONS_PRESENT_AT_BOOT
    	default 0
    	depends on DEMAND_PAGING && MMU
    	help
    	  This sets the number of page frames that will be reserved for
    	  paging that do not count towards free memory. This is to
    	  ensure that there are some page frames available for paging
    	  code and data. Otherwise, it would be possible to exhaust
    	  all page frames via anonymous memory mappings.

*(The 'depends on' condition includes propagated dependencies from ifs and menus.)*