arch/x86/include/asm/sparsemem.h

File Facts

System

Linux kernel

Corpus path

arch/x86/include/asm/sparsemem.h

Extension

.h

Size

830 bytes

Lines

35

Domain

Architecture Layer

Bucket

arch/x86

Inferred role

Architecture Layer: implementation source

Status

source implementation candidate

Why This File Exists

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

• CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• linux/types.h

Detected Declarations

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

Annotated Snippet

#ifndef _ASM_X86_SPARSEMEM_H
#define _ASM_X86_SPARSEMEM_H

#include <linux/types.h>

#ifdef CONFIG_SPARSEMEM
/*
 * generic non-linear memory support:
 *
 * 1) we will not split memory into more chunks than will fit into the flags
 *    field of the struct page
 *
 * SECTION_SIZE_BITS		2^n: size of each section
 * MAX_PHYSMEM_BITS		2^n: max size of physical address space
 *
 */

#ifdef CONFIG_X86_32
# ifdef CONFIG_X86_PAE
#  define SECTION_SIZE_BITS	29
#  define MAX_PHYSMEM_BITS	36
# else
#  define SECTION_SIZE_BITS	26
#  define MAX_PHYSMEM_BITS	32
# endif
#else /* CONFIG_X86_32 */
# define SECTION_SIZE_BITS	27 /* matt - 128 is convenient right now */
# define MAX_PHYSMEM_BITS	(pgtable_l5_enabled() ? 52 : 46)
#endif

#endif /* CONFIG_SPARSEMEM */

#endif /* _ASM_X86_SPARSEMEM_H */

Annotation

• Immediate include surface: `linux/types.h`.
• Atlas domain: Architecture Layer / arch/x86.
• Implementation status: source implementation candidate.

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.