doc: add a FAQ doc

Start a new FAQ document with questions we're often being asked on
support channels.  We'll expand this list over time, and as the number
of questions grow, we'll organize them as appropriate.

Signed-off-by: David B. Kinder <david.b.kinder@intel.com>

doc/faq.rst

@@ -0,0 +1,83 @@
+.. _faq:
+
+FAQ
+###
+
+Here are some frequently asked questions about the ACRN project.
+
+.. contents::
+   :local:
+   :backlinks: entry
+
+------
+
+What hardware does ACRN support?
+********************************
+
+ACRN runs on Intel Apollo Lake and Kaby Lake boards, as documented in
+our :ref:`hardware` documentation.
+
+Clear Linux* fails to boot on my NUC
+************************************
+
+If you're following the :ref:`getting_started` documentation and the NUC
+fails to boot, here are some options to try:
+
+* Upgrade your platform to the latest BIOS
+* Verify Secure Boot is disabled in the BIOS settings:
+
+  - Depending on your platform, press for example, :kbd:`F2` while
+    booting to enter the BIOS options menu, and verify "Secure Boot" is
+    not checked in the "Boot Options"
+* Make sure you are using EFI (and not legacy BIOS)
+
+How do I configure ACRN's memory use?
+*************************************
+
+It's important that the ACRN Kconfig settings are aligned with the physical memory
+on your platform. Check the documentation for these option settings for
+details:
+
+* :option:`CONFIG_PLATFORM_RAM_SIZE`
+* :option:`CONFIG_SOS_RAM_SIZE`
+* :option:`CONFIG_UOS_RAM_SIZE`
+* :option:`CONFIG_HV_RAM_SIZE`
+
+For example, if memory is 32G, setup ``PLATFORM_RAM_SIZE`` = 32G
+
+::
+
+  config PLATFORM_RAM_SIZE
+        hex "Size of the physical platform RAM"
+        default 0x200000000 if PLATFORM_SBL
+        default 0x800000000 if PLATFORM_UEFI
+
+Setup ``SOS_RAM_SIZE`` = 32G too (The SOS will have the whole resource)
+
+::
+
+  config SOS_RAM_SIZE
+        hex "Size of the vm0 (SOS) RAM"
+        default 0x200000000 if PLATFORM_SBL
+        default 0x800000000 if PLATFORM_UEFI
+
+Setup ``UOS_RAM_SIZE`` to what you need, for example,  16G
+
+::
+
+  config UOS_RAM_SIZE
+        hex "Size of the User OS (UOS) RAM"
+        default 0x100000000 if PLATFORM_SBL
+        default 0x400000000 if PLATFORM_UEFI
+
+Setup ``HV_RAM_SIZE`` (we will reserve memory for guest EPT paging
+table), if you setup 32G (default 16G), you must enlarge it with
+(32G-16G)/2M pages (where pages are 4K). The example below is after
+HV_RAM_SIZE is changed to 240M
+
+::
+
+  config HV_RAM_SIZE
+    hex "Size of the RAM region used by the hypervisor"
+    default 0x07800000 if PLATFORM_SBL
+    default 0x0f000000 if PLATFORM_UEFI

doc/index.rst

@@ -31,6 +31,7 @@ Sections
    developer-guides/index.rst
    tutorials/index.rst
    release_notes.rst
+   faq.rst
 
 Indices and Tables
 ******************