Mupen64Plus supports a single data directory and a single plugin directory in
its configuration, yet we need data and plugin files from a variety of
packages.  The best way to deal with this is to install all packages from
which data and plugin files are needed into one's profile, and point the
configuration there.  Hence, the ui-console package provides propagated inputs
for packages with the most important data and plugin files, and this patch
provides the user instructions on what needs to be done in order to have
Mupen64Plus find the relevant data and plugins.

--- a/src/plugin.c
+++ b/src/plugin.c
@@ -122,6 +122,22 @@ m64p_error PluginSearchLoad(m64p_handle ConfigUI)
     {
         const char *plugindir = (*ConfigGetParamString)(ConfigUI, "PluginDir");
         lib_filelist = osal_library_search(plugindir);
+        /* Guix specific */
+        if (lib_filelist == NULL)
+        {
+            DebugMessage(M64MSG_ERROR, "No plugins found in PluginDir path: %s", plugindir);
+            DebugMessage(M64MSG_ERROR,
+                         "\n\n"
+                         "*********************************\n"
+                         "*** Notice for GNU Guix users ***\n"
+                         "*********************************\n"
+                         "\n"
+                         "You might want to edit your mupen64plus.cfg (in $XDG_CONFIG_HOME by default)\n"
+                         "and set SharedDataPath to /path/to/my_guix_profile/share/mupen64plus and\n"
+                         "PluginDir to /path/to/my_guix_profile/lib/mupen64plus so that data and plugins\n"
+                         "are found.\n"
+                         "\n");
+        }
     }
 
     /* if still no plugins found, search some common system folders */
'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=670dcc8e4c56413d646c034d0c382bd6977992eb'>root</a>/<a href='/guix/log/gnu?id=670dcc8e4c56413d646c034d0c382bd6977992eb'>gnu</a>/<a href='/guix/log/gnu/bootloader?id=670dcc8e4c56413d646c034d0c382bd6977992eb'>bootloader</a>/<a href='/guix/log/gnu/bootloader/depthcharge.scm?id=670dcc8e4c56413d646c034d0c382bd6977992eb'>depthcharge.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/bootloader/depthcharge.scm?id=670dcc8e4c56413d646c034d0c382bd6977992eb&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-05-20 08:30:35 -0400'>2020-05-20</span></td><td><a href='/guix/commit/gnu/bootloader/depthcharge.scm?id=b460ba7992a0b4af2ddb5927dcf062784539ef7b'>bootloader: grub: Allow booting from a Btrfs subvolume.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/bootloader/grub.scm (strip-mount-point): Remove procedure.
(normalize-file): Add procedure.
(grub-configuration-file): New BTRFS-SUBVOLUME-FILE-NAME parameter.  When
defined, prepend its value to the kernel and initrd file names, using the
NORMALIZE-FILE procedure.  Adjust the call to EYE-CANDY to pass the
BTRFS-SUBVOLUME-FILE-NAME argument.  Normalize the KEYMAP file as well.
(eye-candy): Add a BTRFS-SUBVOLUME-FILE-NAME parameter, and use it, along with
the NORMALIZE-FILE procedure, to normalize the FONT-FILE and IMAGE nested
variables.  Adjust doc.
* gnu/bootloader/depthcharge.scm (depthcharge-configuration-file): Adapt.
* gnu/bootloader/extlinux.scm (extlinux-configuration-file): Likewise.
* gnu/system/file-systems.scm (btrfs-subvolume?)
(btrfs-store-subvolume-file-name): New procedures.
* gnu/system.scm (operating-system-bootcfg): Specify the Btrfs
subvolume file name the store resides on to the
`operating-system-bootcfg' procedure, using the new
BTRFS-SUBVOLUME-FILE-NAME argument.
* doc/guix.texi (File Systems): Add a Btrfs subsection to document the use of
subvolumes.
* gnu/tests/install.scm (%btrfs-root-on-subvolume-os)
(%btrfs-root-on-subvolume-os-source)
(%btrfs-root-on-subvolume-installation-script)
(%test-btrfs-root-on-subvolume-os): New variables.
</span></span></td><td>Maxim Cournoyer</td></tr>