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* faq-using.xml (faq.using.multiple-copies): Modernize to reflect

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installation separation since Cygwin 1.7.
	(faq.using.third-party.multiple-copies): Ditto.
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Corinna Vinschen
2013-06-19 08:42:48 +00:00
parent 9a52d79f10
commit f2407e2210
2 changed files with 37 additions and 14 deletions
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6
winsup/doc/ChangeLog
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@@ -1,3 +1,9 @@
2013-06-19 Corinna Vinschen <corinna@vinschen.de>
* faq-using.xml (faq.using.multiple-copies): Modernize to reflect
installation separation since Cygwin 1.7.
(faq.using.third-party.multiple-copies): Ditto.
2013-06-17 Corinna Vinschen <corinna@vinschen.de>
* cygwinenv.xml: Fix link to FAQ.

45
winsup/doc/faq-using.xml
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@@ -395,18 +395,33 @@ set is 65001.</para>
<qandaentry id="faq.using.multiple-copies">
<question><para>Is it OK to have multiple copies of the DLL?</para></question>
<answer>
<para>You should only have one copy of the Cygwin DLL on your system. If you
have multiple versions, they will conflict and cause problems.
<para>Yes, as long as they are used in strictly separated installations.</para>
<para>The Cygwin DLL has to handle various sharing situations between
multiple processes. It has to keep a process table. It has to maintain
a mount table which is based on the installation path of the Cygwin DLL.</para>
<para>For that reason, the Cygwin DLL maintains shared resources based on
a hash value created from its own installation path. Each Cygwin DLL
on the machine constitutes a Cygwin installation, with the directory
the Cygwin DLL resides in treated as "/bin", the parent directory as "/".
</para>
<para>Therefore, you can install two or more separate Cygwin distros on
a single machine. Each of these installations use their own Cygwin DLL,
and they don't share the default POSIX paths, nor process tables, nor
any other shared resource used to maintain the installation.</para>
<para>However, a clean separation requires that you don't try to run
executables of one Cygwin installation from processes running in another
Cygwin installation. This may or may not work, but the chances that the
result is not what you expect are pretty high.</para>
<para>If you get the error "shared region is corrupted" or "shared region
version mismatch" it means you have multiple versions of cygwin1.dll
running at the same time which conflict with each other. This could happen,
for example, if you update cygwin1.dll without exiting
<emphasis>all</emphasis> Cygwin apps (including inetd) beforehand.
</para>
running at the same time which conflict with each other. Apart from
mixing executables of different Cygwin installations, this could also happen
if you have one a single Cygwin installation, for example, if you update the
Cygwin package without exiting <emphasis>all</emphasis> Cygwin apps (including
services like sshd) beforehand.</para>
<para>The only DLL that is sanctioned by the Cygwin project is the one that
you get by running <ulink url="http://cygwin.com/setup.exe">setup.exe</ulink>,
installed in the directory controlled by this program. If you have other
installed in a directory controlled by this program. If you have other
versions on your system and desire help from the cygwin project, you should
delete or rename all DLLs that are not installed by
<filename>setup.exe</filename>.
@@ -422,15 +437,17 @@ cygwin-mounted filesystems (as Cygwin 'find' would do).
<qandaentry id="faq.using.third-party.multiple-copies">
<question><para>
I read the above but I want to bundle Cygwin with a product, and ship it
to customer sites. How can I do this without conflicting with any
Cygwin installed by the user?
to customer sites. How can I do this without conflicting with any Cygwin
installed by the user?
</para></question>
<answer><para>
Third party developers who wish to use Cygwin should check if
there is a version of cygwin installed and use the installed
version if it is newer, or conditionally upgrade if it is not.
(If you write a tool to make this easy, consider contributing
it for others to use)
Usually, if you keep your installation separate, nothing bad should happen.
However, for the user's convenience, and to avoid potential problems which
still can occur, consider to integrate your product with an already existing
Cygwin installation on the user's machine, or, if there is none, consider
to install the official Cygwin distro on behalf of the user and integrate
your tools from there. (If you write a tool to make this easy, consider
contributing it for others to use)
</para></answer></qandaentry>
<qandaentry id="faq.using.bundling-cygwin">