Required Kernel Options

General Kernel Options

Enable GPT support.

-*- Enable the block layer  --->
      Partition Types  --->
      [*]   EFI GUID Partition support
      [*]   Windows Logical Disk Manager (Dynamic Disk) support

I also select dynamic disks just in case I need to use disks that were partitioned using XP, Vista, etc.

Processor type and features  --->
   [*] Symmetric multi-processing support
   [*] Machine Check / overheating reporting 
   [*]   Intel MCE Features
   [*]   AMD MCE Features
  Processor family (Generic-x86-64)  --->
    ( ) Opteron/Athlon64/Hammer/K8
    ( ) Intel P4 / older Netburst based Xeon
    (X) Core 2/newer Xeon
    ( ) Intel Atom
    ( ) Generic-x86-64

Executable file formats / Emulations  --->
    [*] IA32 Emulation

Device Drivers --->
  Generic Driver Options --->
    [*] Maintain a devtmpfs filesystem to mount at /dev
    [ ]   Automount devtmpfs at /dev, after the kernel mounted the rootfs

File systems --->
  <*> Second extended fs support
  [*]   Ext2 extended attributes 
  [*]     Ext2 POSIX Access Control Lists
  [*]     Ext2 Security Labels
  [ ]   Ext2 execute in place support (NEW)
  <*> Ext3 journalling file system support
  [*]   Default to 'data=ordered' in ext3 (NEW)
  [*]   Ext3 extended attributes (NEW)
  [*]     Ext3 POSIX Access Control List
  [*]     Ext3 Security Labels
  <*> The Extended 4 (ext4) filesystem
  [*]   Ext4 POSIX Access Control Lists
  [*]   Ext4 Security Labels
  [ ]   EXT4 debugging support (NEW)
  [ ] JBD (ext3) debugging support (NEW)
  [ ] JBD2 (ext4) debugging support (NEW)
  < > Reiserfs support (NEW)
  < > JFS filesystem support (NEW)
  < > XFS filesystem support (NEW)
  < > GFS2 file system support (NEW)
  < > Btrfs filesystem support (NEW)
  < > NILFS2 file system support (NEW)
  [*] Dnotify support (NEW)
  [*] Inotify support for userspace (NEW)
  [*] Filesystem wide access notification
  [ ]   fanotify permissions checking (NEW)
  [*] Quota support
  [*] Report quota messages through netlink interface
  [ ] Print quota warnings to console (OBSOLETE)
  [ ] Additional quota sanity checks (NEW)
  < > Old quota format support (NEW)
  <*> Quota format vfsv0 and vfsv1 support
  <*> Kernel automounter version 4 support (also supports v3)
  <*> FUSE (Filesystem in Userspace) support
  <*>   Character device in Userspace support
      Caches  --->
      CD-ROM/DVD Filesystems  --->
        <*> ISO 9660 CDROM file system support
        [*]   Microsoft Joliet CDROM extensions
        [*]   Transparent decompression extension
        <*> UDF file system support (NEW)
      DOS/FAT/NT Filesystems  --->
        <*> MSDOS fs support
        <*> VFAT (Windows-95) fs support
        (437) Default codepage for FAT (NEW)
        (iso8859-1) Default iocharset for FAT (NEW)
        <*> NTFS file system support
        [ ]   NTFS debugging support (NEW)
        [*]   NTFS write support
      Pseudo filesystems  --->
        -*- /proc file system support
        [*]    /proc/kcore support
        [*]    /proc/vmcore support
        -*- Tmpfs virtual memory file system support (former shm fs)
        [*]    Tmpfs POSIX Access Control Lists
        -*-    Tmpfs extended attributes
        [*] HugeTLB file system support
        <*> Userspace-driven configuration filesystem
  [*] Miscellaneous filesystems (NEW)  --->
  [*] Network File Systems (NEW)  --->
  -*- Native language support  --->

USB support.

Device Drivers --->
  [*] USB support  --->
    <*>   Support for Host-side USB
    [*]   USB verbose debug messages
    [*]   USB announce new devices

Device Drivers --->
  <*> Multimedia support  --->

For RAID and LVM2 support.

http://www.gentoo.org/doc/en/gentoo-x86+raid+lvm2-quickinstall.xml

https://wiki.gentoo.org/wiki/LVM

Device Drivers  --->
   [*] Multiple devices driver support (RAID and LVM)  --->
       <*>   RAID support
       [*]     Autodetect RAID arrays during kernel boot (NEW)
       <*>     Linear (append) mode
       <*>     RAID-0 (striping) mode
       <*>     RAID-1 (mirroring) mode
       <*>     RAID-10 (mirrored striping) mode
       <*>     RAID-4/RAID-5/RAID-6 mode
       < >     Multipath I/O support (NEW)
       < >     Faulty test module for MD (NEW)
       <*>   Block device as cache
       [ ]     Bcache debugging (NEW)
       [ ]     Extended runtime checks (NEW)
       [ ]     Debug closures (NEW)
       <*>   Device mapper support
       [ ]     Device mapper debugging support (NEW)
       <*>     Crypt target support
       <*>     Snapshot target
       < >     Thin provisioning target (NEW)
       <*>     Cache target (EXPERIMENTAL)
       <*>       MQ Cache Policy (EXPERIMENTAL) (NEW)
       <*>       Cleaner Cache Policy (EXPERIMENTAL) (NEW)
       <*>     Mirror target
       < >     RAID 1/4/5/6/10 target (NEW)
       < >   Mirror userspace logging (NEW)
       <*>   Zero target
       <*>   Multipath target
       <*>     I/O Path Selector based on the number of in-flight I/Os
       <*>     I/O Path Selector based on the service time
       < >   I/O delaying target (NEW)
       [*]   DM uevents
       < >   Flakey target (NEW)
       < >   Verity target support (NEW)

Device Drivers  --->
  [*] Network device support --->
      [*] Ethernet driver support --->
         <*>   Realtek 8169 gigabit Ethernet support

Required by X

With the Nouveau Driver in Mind

Device Drivers  --->
    Input device support --->
        <*> Event interface

Device Drivers  --->
    <*> Connector - unified userspace <-> kernelspace linker  --->
    Graphics support  --->
        <*>   Direct Rendering Manager (XFree86 4.1.0 and higher DRI support) --->
        <*>   Nouveau (nVidia) cards
        (5)      Maximum debug level (NEW)
        (3)      Default debug level (NEW)
        [*]      Support for backlight control (NEW)
        -*- Support for frame buffer devices  --->
            ## Disable all drivers, including NVidia, etc.
            [ ]   Enable firmware EDID
            [ ]   Enable Video Mode Handling Helpers
            [ ]   Enable Tile Blitting Support
            < >   VESA VGA graphics support
            [ ]   EFI-based Framebuffer Support
            Console display driver support --->
            -*- Framebuffer Console support

With the NVidia Driver in Mind

Loadable module support --->
    [*] Enable loadable module support

Processor type and features  --->
    -*- MTRR (Memory Type Range Register) support
    [*]    MTRR cleanup support
    (1)       MTRR cleanup enable value (0-1) (NEW)
    (1)       MTRR cleanup spare reg num (0-7) (NEW)

Device Drivers --->
    Graphics Support --->
        -*- /dev/agpgart (AGP Support) --->

Additional Kernel Options

Device Drivers  --->
    [*] Network device support --->
         <*>  Bonding driver support

[*] Virtualization --->
    <*>   Kernel-based Virtual Machine (KVM) support
    <*>   Host kernel accelerator for virtio net (EXPERIMENTAL)

Device Drivers  --->
   <*> Multimedia support --->

Resources

MTRR Linux Kernel
http://coopertronix.com/index.php/gnetoo-linux/gentoo-linux/mtrr-kernel

Gentoo Discussion Forums
https://forums.gentoo.org/viewtopic-t-911866-start-0.html