[PATCH] Add FAQ How do I fix find_fast_cwd warnings?

Brian Inglis Brian.Inglis@SystematicSw.ab.ca
Mon Nov 13 17:12:00 GMT 2017

On 2017-11-13 05:05, Corinna Vinschen wrote:
> On Nov 13 00:04, Brian Inglis wrote:
>> On 2017-11-12 16:02, Ken Brown wrote:
>>> On 11/12/2017 4:27 PM, Brian Inglis wrote:
>>>> +    <para>Some ancient Cygwin releases asked users to report problems that were
>>>> +      difficult to diagnose to the mailing list with the message:</para>
>>>> +
>>>> +    <screen>find_fast_cwd: WARNING: Couldn't compute FAST_CWD pointer. Please
>>>> report
>>>> +    this problem to the public mailing listcygwin@cygwin.com</screen>
>>>> +
>>>> +    <para>These problems were fixed long ago in updated Cygwin releases.</para>
>>> The wording of the warning message was changed 3 years ago, in commit 0793492. 
>>> I'm not sure that qualifies as ancient.  I also don't think it's accurate to
>>> refer to the problem as "difficult to diagnose" or to say that the problems
>>> "were fixed long ago".
>> The original message was added in 2011 - 1.7.10 maybe earlier - NT4 support was
>> dropped around then - pretty ancient in Cygwin terms of how many Windows
>> releases have had support dropped since then!
>>> The issue (Corinna will correct me if I'm wrong) is simply that new releases of
>>> Windows sometimes require changes in how Cygwin finds the fast_cwd pointer.  So
>>> users of old versions of Cygwin on new versions of Windows might have problems,
>>> and this can certainly happen again in the future.  But the FAQ doesn't need to
>>> go into that.  Why not just say what the warning currently says (see
>>> path.cc:find_fast_cwd()):
>>> "This typically occurs if you're using an older Cygwin version on a newer
>>> Windows.  Please update to the latest available Cygwin version from
>>> https://cygwin.com/.  If the problem persists, please see
>>> https://cygwin.com/problems.html."
>>> You can also add your sentence about contacting the vendor who provided the old
>>> Cygwin release.
>> We are trying in the FAQ entry to persuade an annoyed user that it may be in
>> their best interest to do some remediation, rather than just complain in an
>> email to an org they think is a company (cygwin.com) they have never heard of,
>> who they expect from their application message to take care of their problem
>> with no other effort on their part, and who they can blame if nothing happens.
>> Assuming they find the FAQ entry, emphatic language may persuade them to do
>> something more than the message says they should do.
> Nevertheless, Ken has a point.
> s/ancient/older and the text should really explain the "older Cygwin on
> newer Windows" problem without necessarily going into too much detail.
> "The problem has been fixed" just doesn't fit the facts.

I guess I may have been a little enthusiastic to get something out there we
could refer to in future - and reduce the annoyance level for both posters and
subscribers - attaching a hopefully more accurate diff for comment, also
addressing some of the other points I suggested.

Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada
-------------- next part --------------
diff --git a/winsup/doc/faq-using.xml b/winsup/doc/faq-using.xml
index b6b152e4e..4ac26cc84 100644
--- a/winsup/doc/faq-using.xml
+++ b/winsup/doc/faq-using.xml
@@ -1419,4 +1419,57 @@ such as virtual memory paging and file caching.</para>
   difficult to make <literal>fork()</literal> work reliably.</para>
+<qandaentry id='faq.using.fixing-find_fast_cwd-warnings'>
+  <question><para>How do I fix <literal>find_fast_cwd</literal> warnings?</para></question>
+  <answer>
+    <para>Older Cygwin releases asked users to report problems to the mailing
+	list with the message:</para>
+    <screen>find_fast_cwd: WARNING: Couldn't compute FAST_CWD pointer. Please report
+	this problem to the public mailing list cygwin@cygwin.com</screen>
+    <para>Recent Cygwin releases changed this to the message:</para>
+    <screen>This typically occurs if you're using an older Cygwin version on a newer Windows.
+	Please update to the latest available Cygwin version from https://cygwin.com/.
+	If the problem persists, please see https://cygwin.com/problems.html."</screen>
+    <para>This happens when the Cygwin release you installed can not find out
+	how to get your current directory from the Windows release you are
+	using.</para>
+    <para>Unfortunately some projects and products still distribute older
+	Cygwin releases, which do not support newer Windows releases, rather
+	than having their product install the current Cygwin release over the
+	Internet.
+	They also provide no information about keeping Cygwin up to date with
+	upgrades and fixes.</para>
+    <para>The fix is simply downloading and running Cygwin Setup, using the
+	instructions at: 
+	<ulink url="https://cygwin.com/cygwin-ug-net/setup-net.html">
+	    Setting Up Cygwin - Internet Setup</ulink>.</para>
+    <para>When running Setup, you should not change most of the values
+	presented, just select the <strong>Next</strong> button in most cases,
+	as you already have a Cygwin release installed and only want to upgrade
+	your current installation.  You should make your own selection if the
+	internet connection to your system requires a proxy, and you have to
+	pick an up to date Cygwin download (mirror) site, preferably the site
+	nearest to your system for faster downloads, as shown with more details on 
+	<ulink url="https://cygwin.com/mirrors.html">
+	    Mirror Sites</ulink>.</para>
+    <para>Cygwin Setup will download and apply updates to all packages required
+	for Cygwin itself and installed applications.
+	Any problems with applying updates or the application after updates should be
+	reported to the project or product vendor for follow up action.</para>
+    <para>As Cygwin is a volunteer project, and we can not provide support for
+	older releases installed by projects or products, but would like to be
+	able to follow up to reduce these issues, it would be helpful if you
+	would send us a quick
+	<ulink url="mailto:cygwin@cygwin.com&subject=Source%20of%20application%20providing%20Cygwin%20warning%20about%20FAST_CWD">
+	    email</ulink> to let us know about the source of the application
+	which installed the older Cygwin release: whether it was purchased from
+	a vendor or a project downloaded from the Internet, any related web
+	pages, or other details you may have readily available.</para>
+  </answer>

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