[RFC PATCH v2 04/26] docs: reporting-bugs: step-by-step guide for issues in stable & longterm

[Thorsten Leemhuis <linux@leemhuis.info>]

Handle stable and longterm kernels in a subsection, as dealing with them
directly in the main part of the step-by-step guide turned out to make
it messy and hard to follow: it looked a bit like code with a large
amount of if-then-else section to handle special cases, which made the
typical flow hard to understand.

Yet again a reference section will later describe each step in more
detail and repeat each step as introduction.

Signed-off-by: Thorsten Leemhuis <linux@leemhuis.info>
---
 Documentation/admin-guide/reporting-bugs.rst | 48 ++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/Documentation/admin-guide/reporting-bugs.rst b/Documentation/admin-guide/reporting-bugs.rst
index a654c54d7dc6..2b48c824d070 100644
--- a/Documentation/admin-guide/reporting-bugs.rst
+++ b/Documentation/admin-guide/reporting-bugs.rst
@@ -162,6 +162,54 @@ After these preparations you'll now enter the main part:
    help yourself, if you don't get any help or if it's unsatisfying.
 
 
+Reporting issues only occurring in older kernel version lines
+-------------------------------------------------------------
+
+This section is for you, if you tried the latest mainline kernel as outlined
+above, but failed to reproduce your issue there; at the same time you want to
+see the issue fixed in older version lines or a vendor kernel that's regularly
+rebased on new stable or longterm releases. If that case follow these steps:
+
+ * Prepare yourself for the possibility that going through the next few steps
+   might not get the issue solved in older releases: the fix might be too big
+   or risky to get backported there.
+
+ * Check if the kernel developers still maintain the Linux kernel version
+   line you care about: go to the front page of kernel.org and make sure it
+   mentions the latest release of the particular version line without an
+   '[EOL]' tag.
+
+ * Check the archives of the Linux stable mailing list for existing reports.
+
+ * Install the latest release from the particular version line as a vanilla
+   kernel. Ensure this kernel is not tainted and still shows the problem, as
+   the issue might have already been fixed there.
+
+ * Search the Linux kernel version control system for the change that fixed
+   the issue in mainline, as its commit message might tell you if the fix is
+   scheduled for backporting already. If you don't find anything that way,
+   search the appropriate mailing lists for posts that discuss such an issue
+   or peer-review possible fixes; then check the discussions if the fix was
+   deemed unsuitable for backporting. If backporting was not considered at
+   all, join the newest discussion, asking if it's in the cards.
+
+ * Check if you're dealing with a regression that was never present in
+   mainline by installing the first release of the version line you care
+   about. If the issue doesn't show up with it, you basically need to report
+   the issue with this version like you would report a problem with mainline
+   (see above). This ideally includes a bisection followed by a search for
+   existing reports on the net; with the help of the subject and the two
+   relevant commit-ids. If that doesn't turn up anything, write the report; CC
+   or forward the report to the stable maintainers, the stable mailing list,
+   and those who authored the change. Include the shortened commit-id if you
+   found the change that causes it.
+
+ * One of the former steps should lead to a solution. If that doesn't work
+   out, ask the maintainers for the subsystem that seems to be causing the
+   issue for advice; CC the mailing list for the particular subsystem as well
+   as the stable mailing list.
+
+
 .. ############################################################################
 .. Temporary marker added while this document is rewritten. Sections above
 .. are new and dual-licensed under GPLv2+ and CC-BY 4.0, those below are old.
-- 
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