arch/nios2/include/asm/pgtable-bits.h

Source file repositories/reference/linux-study-clean/arch/nios2/include/asm/pgtable-bits.h

File Facts

System
Linux kernel
Corpus path
arch/nios2/include/asm/pgtable-bits.h
Extension
.h
Size
1177 bytes
Lines
38
Domain
Architecture Layer
Bucket
arch/nios2
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.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef _ASM_NIOS2_PGTABLE_BITS_H
#define _ASM_NIOS2_PGTABLE_BITS_H

/*
 * These are actual hardware defined protection bits in the tlbacc register
 * which looks like this:
 *
 * 31 30 ... 26 25 24 23 22 21 20 19 18 ...  1  0
 * ignored........  C  R  W  X  G PFN............
 */
#define _PAGE_GLOBAL	(1<<20)
#define _PAGE_EXEC	(1<<21)
#define _PAGE_WRITE	(1<<22)
#define _PAGE_READ	(1<<23)
#define _PAGE_CACHED	(1<<24)	/* C: data access cacheable */

/*
 * Software defined bits. They are ignored by the hardware and always read back
 * as zero, but can be written as non-zero.
 */
#define _PAGE_PRESENT	(1<<25)	/* PTE contains a translation */
#define _PAGE_ACCESSED	(1<<26)	/* page referenced */
#define _PAGE_DIRTY	(1<<27)	/* dirty page */

/* We borrow bit 31 to store the exclusive marker in swap PTEs. */
#define _PAGE_SWP_EXCLUSIVE	(1<<31)

#endif /* _ASM_NIOS2_PGTABLE_BITS_H */

Annotation

Implementation Notes