Documentation/arch/s390/mm.rst

Source file repositories/reference/linux-study-clean/Documentation/arch/s390/mm.rst

File Facts

System: Linux kernel
Corpus path: Documentation/arch/s390/mm.rst
Extension: .rst
Size: 3438 bytes
Lines: 116
Domain: Support Tooling And Documentation
Bucket: Documentation
Inferred role: Support Tooling And Documentation: documentation
Status: atlas-only

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.
Allocates kernel memory; connect allocation flags and lifetime to context constraints.
Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

No C-style include directives detected by the generator.

Detected Declarations

No top-level syscall, struct, function, initcall, or export declaration detected by the generator.

Annotated Snippet

.. SPDX-License-Identifier: GPL-2.0

=================
Memory Management
=================

Virtual memory layout
=====================

.. note::

 - Some aspects of the virtual memory layout setup are not
   clarified (number of page levels, alignment, DMA memory).

 - Unused gaps in the virtual memory layout could be present
   or not - depending on how partucular system is configured.
   No page tables are created for the unused gaps.

 - The virtual memory regions are tracked or untracked by KASAN
   instrumentation, as well as the KASAN shadow memory itself is
   created only when CONFIG_KASAN configuration option is enabled.

::

  =============================================================================
  |    Physical      |	  Virtual	| VM area description
  =============================================================================
  +- 0 --------------+- 0 --------------+
  |		     | S390_lowcore	| Low-address memory
  |		     +- 8 KB -----------+
  |		     |			|
  |		     |			|
  |		     | ... unused gap	| KASAN untracked
  |		     |			|
  +- AMODE31_START --+- AMODE31_START --+ .amode31 rand. phys/virt start
  |.amode31 text/data|.amode31 text/data| KASAN untracked
  +- AMODE31_END ----+- AMODE31_END ----+ .amode31 rand. phys/virt end (<2GB)
  |		     |			|
  |		     |			|
  +- __kaslr_offset_phys		| kernel rand. phys start
  |		     |			|
  | kernel text/data |			|
  |		     |			|
  +------------------+			| kernel phys end
  |		     |			|
  |		     |			|
  |		     |			|
  |		     |			|
  +- ident_map_size -+			|
		     |			|
		     |	... unused gap	| KASAN untracked
		     |			|
		     +- __identity_base + identity mapping start (>= 2GB)
		     |			|
		     | identity		| phys == virt - __identity_base
		     | mapping		| virt == phys + __identity_base
		     |			|
		     |			| KASAN tracked
		     |			|
		     |			|
		     |			|
		     |			|
		     |			|
		     |			|
		     |			|
		     |			|
		     |			|
		     |			|
		     |			|
		     |			|

Annotation

Atlas domain: Support Tooling And Documentation / Documentation.
Implementation status: atlas-only.

Implementation Notes

This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.