arch/s390/include/asm/chpid.h

File Facts

System

Linux kernel

Corpus path

arch/s390/include/asm/chpid.h

Extension

.h

Size

979 bytes

Lines

52

Domain

Architecture Layer

Bucket

arch/s390

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

• uapi/asm/chpid.h
• asm/cio.h

Detected Declarations

• struct channel_path_desc_fmt0
• function chp_id_init
• function chp_id_is_equal
• function chp_id_next
• function chp_id_is_valid

Annotated Snippet

struct channel_path_desc_fmt0 {
	u8 flags;
	u8 lsn;
	u8 desc;
	u8 chpid;
	u8 swla;
	u8 zeroes;
	u8 chla;
	u8 chpp;
} __packed;

static inline void chp_id_init(struct chp_id *chpid)
{
	memset(chpid, 0, sizeof(struct chp_id));
}

static inline int chp_id_is_equal(struct chp_id *a, struct chp_id *b)
{
	return (a->id == b->id) && (a->cssid == b->cssid);
}

static inline void chp_id_next(struct chp_id *chpid)
{
	if (chpid->id < __MAX_CHPID)
		chpid->id++;
	else {
		chpid->id = 0;
		chpid->cssid++;
	}
}

static inline int chp_id_is_valid(struct chp_id *chpid)
{
	return (chpid->cssid <= __MAX_CSSID);
}


#define chp_id_for_each(c) \
	for (chp_id_init(c); chp_id_is_valid(c); chp_id_next(c))
#endif /* _ASM_S390_CHPID_H */

Annotation

• Immediate include surface: `uapi/asm/chpid.h`, `asm/cio.h`.
• Detected declarations: `struct channel_path_desc_fmt0`, `function chp_id_init`, `function chp_id_is_equal`, `function chp_id_next`, `function chp_id_is_valid`.
• Atlas domain: Architecture Layer / arch/s390.
• 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.