Cleanup install docs.

doc/install.html

@@ -122,7 +122,7 @@ operating systems, CPUs and compilers:
 <tr class="even">
 <td class="compatcpu">x64 (64 bit)</td>
 <td class="compatos">GCC 4.2+</td>
-<td class="compatos">ORBIS (<a href="#ps4">PS4</a>)</td>
+<td class="compatos">GCC 4.2+<br>ORBIS (<a href="#ps4">PS4</a>)</td>
 <td class="compatos">XCode 5.0+<br>Clang</td>
 <td class="compatos">MSVC + SDK v7.0<br>WinSDK v7.0<br>Durango (<a href="#xboxone">Xbox One</a>)</td>
 </tr>
@@ -202,7 +202,7 @@ which is probably the default on your system, anyway. Simply run:
 make
 </pre>
 <p>
-This always builds a native x86, x64 or PPC binary, depending on the host OS
+This always builds a native binary, depending on the host OS
 you're running this command on. Check the section on
 <a href="#cross">cross-compilation</a> for more options.
 </p>
@@ -333,25 +333,36 @@ directory where <tt>luajit.exe</tt> is installed
 
 <h2 id="cross">Cross-compiling LuaJIT</h2>
 <p>
+First, let's clear up some terminology:
+</p>
+<ul>
+<li>Host: This is your development system, usually based on a x64 or x86 CPU.</li>
+<li>Target: This is the target system you want LuaJIT to run on, e.g. Android/ARM.</li>
+<li>Toolchain: This comprises a C compiler, linker, assembler and a matching C library.</li>
+<li>Host (or system) toolchain: This is the toolchain used to build native binaries for your host system.</li>
+<li>Cross-compile toolchain: This is the toolchain used to build binaries for the target system. They can only be run on the target system.</li>
+</ul>
+<p>
 The GNU Makefile-based build system allows cross-compiling on any host
-for any supported target, as long as both architectures have the same
-pointer size. If you want to cross-compile to any 32 bit target on an
-x64 OS, you need to install the multilib development package (e.g.
-<tt>libc6-dev-i386</tt> on Debian/Ubuntu) and build a 32 bit host part
-(<tt>HOST_CC="gcc -m32"</tt>).
+for any supported target:
 </p>
+<ul>
+<li>Yes, you need a toolchain for both your host <em>and</em> your target!</li>
+<li>Both host and target architectures must have the same pointer size.</li>
+<li>E.g. if you want to cross-compile to a 32 bit target on a 64 bit host, you need to install the multilib development package (e.g. <tt>libc6-dev-i386</tt> on Debian/Ubuntu) and build a 32 bit host part (<tt>HOST_CC="gcc -m32"</tt>).</li>
+<li>64 bit targets always require compilation on a 64 bit host.</li>
+</ul>
 <p>
 You need to specify <tt>TARGET_SYS</tt> whenever the host OS and the
-target OS differ, or you'll get assembler or linker errors. E.g. if
-you're compiling on a Windows or OSX host for embedded Linux or Android,
-you need to add <tt>TARGET_SYS=Linux</tt> to the examples below. For a
-minimal target OS, you may need to disable the built-in allocator in
-<tt>src/Makefile</tt> and use <tt>TARGET_SYS=Other</tt>. Don't forget to
-specify the same <tt>TARGET_SYS</tt> for the install step, too.
+target OS differ, or you'll get assembler or linker errors:
 </p>
+<ul>
+<li>E.g. if you're compiling on a Windows or OSX host for embedded Linux or Android, you need to add <tt>TARGET_SYS=Linux</tt> to the examples below.</li>
+<li>For a minimal target OS, you may need to disable the built-in allocator in <tt>src/Makefile</tt> and use <tt>TARGET_SYS=Other</tt>.</li>
+<li>Don't forget to specify the same <tt>TARGET_SYS</tt> for the install step, too.</li>
+</ul>
 <p>
-The examples below only show some popular targets &mdash; please check
-the comments in <tt>src/Makefile</tt> for more details.
+Here are some examples where host and target have the same CPU:
 </p>
 <pre class="code">
 # Cross-compile to a 32 bit binary on a multilib x64 OS
@@ -369,26 +380,30 @@ use the canonical toolchain triplets for Linux.
 </p>
 <p>
 Since there's often no easy way to detect CPU features at runtime, it's
-important to compile with the proper CPU or architecture settings. You
-can specify these when building the toolchain yourself. Or add
-<tt>-mcpu=...</tt> or <tt>-march=...</tt> to <tt>TARGET_CFLAGS</tt>. For
-ARM it's important to have the correct <tt>-mfloat-abi=...</tt> setting,
-too. Otherwise LuaJIT may not run at the full performance of your target
-CPU.
+important to compile with the proper CPU or architecture settings:
+</o>
+<ul>
+<li>The best way to get consistent results is to specify the correct settings when building the toolchain yourself.</li>
+<li>For a pre-built, generic toolchain add <tt>-mcpu=...</tt> or <tt>-march=...</tt> and other necessary flags to <tt>TARGET_CFLAGS</tt>.</li>
+<li>For ARM it's important to have the correct <tt>-mfloat-abi=...</tt> setting, too. Otherwise LuaJIT may not run at the full performance of your target CPU.</li>
+<li>For MIPS it's important to select a supported ABI (o32 on MIPS32) and consistently compile your project either with hard-float or soft-float compiler settings. Do not use <tt>-mips16</tt>.</li>
+</ul>
+<p>
+Here are some examples for targets with a different CPU than the host:
 </p>
 <pre class="code">
 # ARM soft-float
 make HOST_CC="gcc -m32" CROSS=arm-linux-gnueabi- \
      TARGET_CFLAGS="-mfloat-abi=soft"
 
-# ARM soft-float ABI with VFP (example for Cortex-A8)
+# ARM soft-float ABI with VFP (example for Cortex-A9)
 make HOST_CC="gcc -m32" CROSS=arm-linux-gnueabi- \
-     TARGET_CFLAGS="-mcpu=cortex-a8 -mfloat-abi=softfp"
+     TARGET_CFLAGS="-mcpu=cortex-a9 -mfloat-abi=softfp"
 
-# ARM hard-float ABI with VFP (armhf, requires recent toolchain)
+# ARM hard-float ABI with VFP (armhf, most modern toolchains)
 make HOST_CC="gcc -m32" CROSS=arm-linux-gnueabihf-
 
-# ARM64 (requires x64 host)
+# ARM64
 make CROSS=aarch64-linux-
 
 # PPC
@@ -400,7 +415,7 @@ make HOST_CC="gcc -m32" CROSS=mips-linux-
 make HOST_CC="gcc -m32" CROSS=mipsel-linux-
 </pre>
 <p>
-You can cross-compile for <b id="android">Android</b> using the <a href="http://developer.android.com/sdk/ndk/index.html"><span class="ext">&raquo;</span>&nbsp;Android NDK</a>.
+You can cross-compile for <b id="android">Android</b> using the <a href="https://developer.android.com/ndk/index.html">Android NDK</a>.
 The environment variables need to match the install locations and the
 desired target platform. E.g. Android&nbsp;4.0 corresponds to ABI level&nbsp;14.
 For details check the folder <tt>docs</tt> in the NDK directory.
@@ -414,7 +429,7 @@ to build/deploy or which lowest common denominator you want to pick:
 # Android/ARM, armeabi (ARMv5TE soft-float), Android 2.2+ (Froyo)
 NDK=/opt/android/ndk
 NDKABI=8
-NDKVER=$NDK/toolchains/arm-linux-androideabi-4.6
+NDKVER=$NDK/toolchains/arm-linux-androideabi-4.9
 NDKP=$NDKVER/prebuilt/linux-x86/bin/arm-linux-androideabi-
 NDKF="--sysroot $NDK/platforms/android-$NDKABI/arch-arm"
 make HOST_CC="gcc -m32" CROSS=$NDKP TARGET_FLAGS="$NDKF"
@@ -422,16 +437,16 @@ make HOST_CC="gcc -m32" CROSS=$NDKP TARGET_FLAGS="$NDKF"
 # Android/ARM, armeabi-v7a (ARMv7 VFP), Android 4.0+ (ICS)
 NDK=/opt/android/ndk
 NDKABI=14
-NDKVER=$NDK/toolchains/arm-linux-androideabi-4.6
+NDKVER=$NDK/toolchains/arm-linux-androideabi-4.9
 NDKP=$NDKVER/prebuilt/linux-x86/bin/arm-linux-androideabi-
 NDKF="--sysroot $NDK/platforms/android-$NDKABI/arch-arm"
 NDKARCH="-march=armv7-a -mfloat-abi=softfp -Wl,--fix-cortex-a8"
 make HOST_CC="gcc -m32" CROSS=$NDKP TARGET_FLAGS="$NDKF $NDKARCH"
 
-# Android/MIPS, mips (MIPS32R1 hard-float), Android 4.0+ (ICS)
+# Android/MIPS, mipsel (MIPS32R1 hard-float), Android 4.0+ (ICS)
 NDK=/opt/android/ndk
 NDKABI=14
-NDKVER=$NDK/toolchains/mipsel-linux-android-4.6
+NDKVER=$NDK/toolchains/mipsel-linux-android-4.9
 NDKP=$NDKVER/prebuilt/linux-x86/bin/mipsel-linux-android-
 NDKF="--sysroot $NDK/platforms/android-$NDKABI/arch-mips"
 make HOST_CC="gcc -m32" CROSS=$NDKP TARGET_FLAGS="$NDKF"
@@ -439,7 +454,7 @@ make HOST_CC="gcc -m32" CROSS=$NDKP TARGET_FLAGS="$NDKF"
 # Android/x86, x86 (i686 SSE3), Android 4.0+ (ICS)
 NDK=/opt/android/ndk
 NDKABI=14
-NDKVER=$NDK/toolchains/x86-4.6
+NDKVER=$NDK/toolchains/x86-4.9
 NDKP=$NDKVER/prebuilt/linux-x86/bin/i686-linux-android-
 NDKF="--sysroot $NDK/platforms/android-$NDKABI/arch-x86"
 make HOST_CC="gcc -m32" CROSS=$NDKP TARGET_FLAGS="$NDKF"