heads' kernel


  1. Background
  2. ==========
  3. The upstream Linux kernel maintainers only fix bugs for specific kernel
  4. versions. Those versions include the current "release candidate" (or -rc)
  5. kernel, any "stable" kernel versions, and any "long term" kernels.
  6. Please see https://www.kernel.org/ for a list of supported kernels. Any
  7. kernel marked with [EOL] is "end of life" and will not have any fixes
  8. backported to it.
  9. If you've found a bug on a kernel version isn't listed on kernel.org,
  10. contact your Linux distribution or embedded vendor for support.
  11. Alternatively, you can attempt to run one of the supported stable or -rc
  12. kernels, and see if you can reproduce the bug on that. It's preferable
  13. to reproduce the bug on the latest -rc kernel.
  14. How to report Linux kernel bugs
  15. ===============================
  16. Identify the problematic subsystem
  17. ----------------------------------
  18. Identifying which part of the Linux kernel might be causing your issue
  19. increases your chances of getting your bug fixed. Simply posting to the
  20. generic linux-kernel mailing list (LKML) may cause your bug report to be
  21. lost in the noise of a mailing list that gets 1000+ emails a day.
  22. Instead, try to figure out which kernel subsystem is causing the issue,
  23. and email that subsystem's maintainer and mailing list. If the subsystem
  24. maintainer doesn't answer, then expand your scope to mailing lists like
  25. LKML.
  26. Identify who to notify
  27. ----------------------
  28. Once you know the subsystem that is causing the issue, you should send a
  29. bug report. Some maintainers prefer bugs to be reported via bugzilla
  30. (https://bugzilla.kernel.org), while others prefer that bugs be reported
  31. via the subsystem mailing list.
  32. To find out where to send an emailed bug report, find your subsystem or
  33. device driver in the MAINTAINERS file. Search in the file for relevant
  34. entries, and send your bug report to the person(s) listed in the "M:"
  35. lines, making sure to Cc the mailing list(s) in the "L:" lines. When the
  36. maintainer replies to you, make sure to 'Reply-all' in order to keep the
  37. public mailing list(s) in the email thread.
  38. If you know which driver is causing issues, you can pass one of the driver
  39. files to the get_maintainer.pl script:
  40. perl scripts/get_maintainer.pl -f <filename>
  41. If it is a security bug, please copy the Security Contact listed in the
  42. MAINTAINERS file. They can help coordinate bugfix and disclosure. See
  43. Documentation/SecurityBugs for more information.
  44. If you can't figure out which subsystem caused the issue, you should file
  45. a bug in kernel.org bugzilla and send email to
  46. linux-kernel@vger.kernel.org, referencing the bugzilla URL. (For more
  47. information on the linux-kernel mailing list see
  48. http://www.tux.org/lkml/).
  49. Tips for reporting bugs
  50. -----------------------
  51. If you haven't reported a bug before, please read:
  52. http://www.chiark.greenend.org.uk/~sgtatham/bugs.html
  53. http://www.catb.org/esr/faqs/smart-questions.html
  54. It's REALLY important to report bugs that seem unrelated as separate email
  55. threads or separate bugzilla entries. If you report several unrelated
  56. bugs at once, it's difficult for maintainers to tease apart the relevant
  57. data.
  58. Gather information
  59. ------------------
  60. The most important information in a bug report is how to reproduce the
  61. bug. This includes system information, and (most importantly)
  62. step-by-step instructions for how a user can trigger the bug.
  63. If the failure includes an "OOPS:", take a picture of the screen, capture
  64. a netconsole trace, or type the message from your screen into the bug
  65. report. Please read "Documentation/oops-tracing.txt" before posting your
  66. bug report. This explains what you should do with the "Oops" information
  67. to make it useful to the recipient.
  68. This is a suggested format for a bug report sent via email or bugzilla.
  69. Having a standardized bug report form makes it easier for you not to
  70. overlook things, and easier for the developers to find the pieces of
  71. information they're really interested in. If some information is not
  72. relevant to your bug, feel free to exclude it.
  73. First run the ver_linux script included as scripts/ver_linux, which
  74. reports the version of some important subsystems. Run this script with
  75. the command "sh scripts/ver_linux".
  76. Use that information to fill in all fields of the bug report form, and
  77. post it to the mailing list with a subject of "PROBLEM: <one line
  78. summary from [1.]>" for easy identification by the developers.
  79. [1.] One line summary of the problem:
  80. [2.] Full description of the problem/report:
  81. [3.] Keywords (i.e., modules, networking, kernel):
  82. [4.] Kernel information
  83. [4.1.] Kernel version (from /proc/version):
  84. [4.2.] Kernel .config file:
  85. [5.] Most recent kernel version which did not have the bug:
  86. [6.] Output of Oops.. message (if applicable) with symbolic information
  87. resolved (see Documentation/oops-tracing.txt)
  88. [7.] A small shell script or example program which triggers the
  89. problem (if possible)
  90. [8.] Environment
  91. [8.1.] Software (add the output of the ver_linux script here)
  92. [8.2.] Processor information (from /proc/cpuinfo):
  93. [8.3.] Module information (from /proc/modules):
  94. [8.4.] Loaded driver and hardware information (/proc/ioports, /proc/iomem)
  95. [8.5.] PCI information ('lspci -vvv' as root)
  96. [8.6.] SCSI information (from /proc/scsi/scsi)
  97. [8.7.] Other information that might be relevant to the problem
  98. (please look in /proc and include all information that you
  99. think to be relevant):
  100. [X.] Other notes, patches, fixes, workarounds:
  101. Follow up
  102. =========
  103. Expectations for bug reporters
  104. ------------------------------
  105. Linux kernel maintainers expect bug reporters to be able to follow up on
  106. bug reports. That may include running new tests, applying patches,
  107. recompiling your kernel, and/or re-triggering your bug. The most
  108. frustrating thing for maintainers is for someone to report a bug, and then
  109. never follow up on a request to try out a fix.
  110. That said, it's still useful for a kernel maintainer to know a bug exists
  111. on a supported kernel, even if you can't follow up with retests. Follow
  112. up reports, such as replying to the email thread with "I tried the latest
  113. kernel and I can't reproduce my bug anymore" are also helpful, because
  114. maintainers have to assume silence means things are still broken.
  115. Expectations for kernel maintainers
  116. -----------------------------------
  117. Linux kernel maintainers are busy, overworked human beings. Some times
  118. they may not be able to address your bug in a day, a week, or two weeks.
  119. If they don't answer your email, they may be on vacation, or at a Linux
  120. conference. Check the conference schedule at LWN.net for more info:
  121. https://lwn.net/Calendar/
  122. In general, kernel maintainers take 1 to 5 business days to respond to
  123. bugs. The majority of kernel maintainers are employed to work on the
  124. kernel, and they may not work on the weekends. Maintainers are scattered
  125. around the world, and they may not work in your time zone. Unless you
  126. have a high priority bug, please wait at least a week after the first bug
  127. report before sending the maintainer a reminder email.
  128. The exceptions to this rule are regressions, kernel crashes, security holes,
  129. or userspace breakage caused by new kernel behavior. Those bugs should be
  130. addressed by the maintainers ASAP. If you suspect a maintainer is not
  131. responding to these types of bugs in a timely manner (especially during a
  132. merge window), escalate the bug to LKML and Linus Torvalds.
  133. Thank you!
  134. [Some of this is taken from Frohwalt Egerer's original linux-kernel FAQ]