Documentation/arch/s390/s390dbf.rst

File Facts

System

Linux kernel

Corpus path

Documentation/arch/s390/s390dbf.rst

Extension

.rst

Size

16799 bytes

Lines

508

Domain

Support Tooling And Documentation

Bucket

Documentation

Inferred role

Support Tooling And Documentation: exported/initcall integration point

Status

integration implementation candidate

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.
• Exports symbols or registers init work; inspect boot/module ordering and who consumes the exported contract.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• linux/init.h
• asm/debug.h

Detected Declarations

• struct debug_view
• function init
• function cleanup
• function init
• function cleanup
• function debug_test_format_fn
• module init init
• module init init

Annotated Snippet

module_init(init);
  module_exit(cleanup);

.. code-block:: c

  /*
   * sprintf-view Example
   */

  #include <linux/init.h>
  #include <asm/debug.h>

  static debug_info_t *debug_info;

  static int init(void)
  {
      /* register 4 debug areas with one page each and data field for */
      /* format string pointer + 2 varargs (= 3 * sizeof(long))       */

      debug_info = debug_register("test", 1, 4, sizeof(long) * 3);
      debug_register_view(debug_info, &debug_sprintf_view);

      debug_sprintf_event(debug_info, 2 , "first event in %s:%i\n",__FILE__,__LINE__);
      debug_sprintf_exception(debug_info, 1, "pointer to debug info: %p\n",&debug_info);

      return 0;
  }

  static void cleanup(void)
  {
      debug_unregister(debug_info);
  }

  module_init(init);
  module_exit(cleanup);

Debugfs Interface
-----------------
Views to the debug logs can be investigated through reading the corresponding
debugfs-files:

Example::

  > ls /sys/kernel/debug/s390dbf/dasd
  flush  hex_ascii  level pages
  > cat /sys/kernel/debug/s390dbf/dasd/hex_ascii | sort -k2,2 -s
  00 00974733272:680099 2 - 02 0006ad7e  07 ea 4a 90 | ....
  00 00974733272:682210 2 - 02 0006ade6  46 52 45 45 | FREE
  00 00974733272:682213 2 - 02 0006adf6  07 ea 4a 90 | ....
  00 00974733272:682281 1 * 02 0006ab08  41 4c 4c 43 | EXCP
  01 00974733272:682284 2 - 02 0006ab16  45 43 4b 44 | ECKD
  01 00974733272:682287 2 - 02 0006ab28  00 00 00 04 | ....
  01 00974733272:682289 2 - 02 0006ab3e  00 00 00 20 | ...
  01 00974733272:682297 2 - 02 0006ad7e  07 ea 4a 90 | ....
  01 00974733272:684384 2 - 00 0006ade6  46 52 45 45 | FREE
  01 00974733272:684388 2 - 00 0006adf6  07 ea 4a 90 | ....

See section about predefined views for explanation of the above output!

Changing the debug level
------------------------

Example::


  > cat /sys/kernel/debug/s390dbf/dasd/level
  3
  > echo "5" > /sys/kernel/debug/s390dbf/dasd/level
  > cat /sys/kernel/debug/s390dbf/dasd/level
  5

Annotation

• Immediate include surface: `linux/init.h`, `asm/debug.h`.
• Detected declarations: `struct debug_view`, `function init`, `function cleanup`, `function init`, `function cleanup`, `function debug_test_format_fn`, `module init init`, `module init init`.
• Atlas domain: Support Tooling And Documentation / Documentation.
• 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.