FAQ/install: adjust wording around OS X SIP (#1799)

Author: borsboom

doc/faq.md

@@ -294,27 +294,25 @@ These are written to `*.dump-*` files inside the package's `.stack-work` directo
 
 #### Why is DYLD_LIBRARY_PATH ignored?
 
-<a name="disable-rootless"></a><a name="dyld-library-path-ignored"></a>If you
-are on Mac OS X 10.11 ("El Capitan") or later, System Integrity Protection
-(a.k.a. "rootless")
-[prevents the `DYLD_LIBRARY_PATH` environment variable from being passed to sub-processes](https://github.com/commercialhaskell/stack/issues/1161).
-The only workaround we are aware of is
-[disabling System Integrity Protection](http://osxdaily.com/2015/10/05/disable-rootless-system-integrity-protection-mac-os-x/):
+<a name="dyld-library-path-ignored"></a>If you
+are on Mac OS X 10.11 ("El Capitan") or later, there are upstream issues which
+[prevents the `DYLD_LIBRARY_PATH` environment variable from being passed to GHC](https://github.com/commercialhaskell/stack/issues/1161)
+when System Integrity Protection (a.k.a. "rootless") is enabled. The only
+workaround we are aware of is
+[disabling System Integrity Protection](http://osxdaily.com/2015/10/05/disable-rootless-system-integrity-protection-mac-os-x/).
 
- 1. Reboot into recovery mode (hold down Cmd-R at boot)
- 2. Open a terminal (select __Terminal__ from the __Utilities__ menu)
- 3. Run `csrutil disable; reboot`
-
-Note that this reduces the security of your system.
+**WARNING: Disabling SIP will severely reduce the security of your system, so only do this if absolutely necessary!**
 
 #### Why do I get a `/usr/bin/ar: permission denied` error?
 
-<a name="usr-bin-ar-permission-denied"></a>On OS X 10.11 ("El Capitan") and
-later, this is
-[caused by System Integrity Protection (a.k.a. "rootless")](https://github.com/commercialhaskell/stack/issues/563).
+<a name="usr-bin-ar-permission-denied"></a>If you are on OS X 10.11 ("El Capitan") or
+later, GHC 7.8.4 is
+[incompatible with System Integrity Protection (a.k.a. "rootless")](https://github.com/commercialhaskell/stack/issues/563).
 GHC 7.10.2 includes a fix, so this only effects users of GHC 7.8.4. If you
 cannot upgrade to GHC 7.10.2, you can work around it by
-[disabling System Integrity Protection](#disable-rootless)
+[disabling System Integrity Protection](http://osxdaily.com/2015/10/05/disable-rootless-system-integrity-protection-mac-os-x/).
+
+**WARNING: Disabling SIP will severely reduce the security of your system, so only do this if absolutely necessary!**
 
 #### Why is the `--` argument separator ignored in Windows PowerShell
 

doc/install_and_upgrade.md

@@ -54,14 +54,12 @@ such.
 
 ## Mac OS X
 
-Note: if you are on OS X 10.11 ("El Capitan") or later, System Integrity
-Protection (a.k.a. "rootless") can cause two problems:
+Note: if you are on OS X 10.11 ("El Capitan") and encounter either of these
+problems, see the linked FAQ entries.
 
   * [GHC 7.8.4 fails with `/usr/bin/ar: permission denied`](faq.html#usr-bin-ar-permission-denied)
   * [DYLD_LIBRARY_PATH is ignored](faq.html#dyld-library-path-ignored)
 
-See the above FAQ links for workarounds.
-
 ### Using Homebrew
 
 If you have a popular [brew](http://brew.sh/) tool installed, you can just do: