arch/sparc/lib/ipcsum.S

File Facts

System

Linux kernel

Corpus path

arch/sparc/lib/ipcsum.S

Extension

.S

Size

709 bytes

Lines

37

Domain

Architecture Layer

Bucket

arch/sparc

Inferred role

Architecture Layer: exported/initcall integration point

Status

integration 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.
• Exports symbols or registers init work; inspect boot/module ordering and who consumes the exported contract.

Dependency Surface

• linux/export.h
• linux/linkage.h

Detected Declarations

• export ip_fast_csum

Annotated Snippet

#include <linux/export.h>
#include <linux/linkage.h>

	.text
ENTRY(ip_fast_csum) /* %o0 = iph, %o1 = ihl */
	sub	%o1, 4, %g7
	lduw	[%o0 + 0x00], %o2
	lduw	[%o0 + 0x04], %g2
	lduw	[%o0 + 0x08], %g3
	addcc	%g2, %o2, %o2
	lduw	[%o0 + 0x0c], %g2
	addccc	%g3, %o2, %o2
	lduw	[%o0 + 0x10], %g3

	addccc	%g2, %o2, %o2
	addc	%o2, %g0, %o2
1:	addcc	%g3, %o2, %o2
	add	%o0, 4, %o0
	addccc	%o2, %g0, %o2
	subcc	%g7, 1, %g7
	be,a,pt	%icc, 2f
	 sll	%o2, 16, %g2

	lduw	[%o0 + 0x10], %g3
	ba,pt	%xcc, 1b
	 nop
2:	addcc	%o2, %g2, %g2
	srl	%g2, 16, %o2
	addc	%o2, %g0, %o2
	xnor	%g0, %o2, %o2
	set	0xffff, %o1
	retl
	 and	%o2, %o1, %o0
ENDPROC(ip_fast_csum)
EXPORT_SYMBOL(ip_fast_csum)

Annotation

• Immediate include surface: `linux/export.h`, `linux/linkage.h`.
• Detected declarations: `export ip_fast_csum`.
• Atlas domain: Architecture Layer / arch/sparc.
• Implementation status: integration 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.