1. Get Buildroot

$ git clone git://git.buildroot.net/buildroot.git buildroot (commit id: 986fa441e49cc180f77704699a6d2bb3627bf86a)

2. Edit config file for imx6qsabresd board

$ vim configs/freescale_imx6qsabresd_defconfig as below
################################################################################################################
# architecture
BR2_arm=y
BR2_BINFMT_ELF=y
BR2_cortex_a9=y
BR2_ARM_ENABLE_NEON=y
BR2_ARM_ENABLE_VFP=y
BR2_ARM_EABIHF=y
BR2_ARM_FPU_VFPV3D16=y
BR2_ARM_INSTRUCTIONS_ARM=y

#toolchain
BR2_TOOLCHAIN_EXTERNAL=y
BR2_TOOLCHAIN_EXTERNAL_LINARO_ARM=y
BR2_TOOLCHAIN_EXTERNAL_DOWNLOAD=y

#Build Options
BR2_DL_DIR="/opt/buildroot/dl"

# patches
BR2_GLOBAL_PATCH_DIR="board/freescale/imx6sabre/patches"

# Linux headers same as kernel, a 3.14 series
BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_3_14=y

# system
BR2_TARGET_GENERIC_GETTY_PORT="ttymxc0"

# kernel
BR2_LINUX_KERNEL=y
BR2_LINUX_KERNEL_CUSTOM_GIT=y
BR2_LINUX_KERNEL_CUSTOM_REPO_URL="git://git.freescale.com/imx/linux-2.6-imx.git"
BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION="rel_imx_3.14.52_1.1.0_ga"
BR2_LINUX_KERNEL_DEFCONFIG="imx_v7"
#BR2_LINUX_KERNEL_UIMAGE=y
BR2_LINUX_KERNEL_ZIMAGE=y
BR2_LINUX_KERNEL_UIMAGE_LOADADDR="0x10008000"
BR2_LINUX_KERNEL_DTS_SUPPORT=y
BR2_LINUX_KERNEL_INTREE_DTS_NAME="imx6q-sabresd"

# filesystem
#BR2_TARGET_ROOTFS_EXT2=y
BR2_TARGET_ROOTFS_TAR=y
BR2_TARGET_ROOTFS_TAR_BZIP2=y

# bootloader
BR2_TARGET_UBOOT=y
BR2_TARGET_UBOOT_BOARDNAME="mx6qsabresd"
BR2_TARGET_UBOOT_FORMAT_IMX=y
BR2_TARGET_UBOOT_CUSTOM_GIT=y
BR2_TARGET_UBOOT_CUSTOM_REPO_URL="git://git.freescale.com/imx/uboot-imx.git"
BR2_TARGET_UBOOT_CUSTOM_REPO_VERSION="rel_imx_3.14.52_1.1.0_ga"
################################################################################################################

3. Build image

$ make freescale_imx6qsabresd_defconfig
$ make -j 8
$ ls output/images/* -alh
-rw-r--r-- 1 vmuser vmuser  42K Apr  7 13:46 output/images/imx6q-sabresd.dtb
-rw-r--r-- 1 vmuser vmuser 8.3M Apr  7 13:46 output/images/rootfs.ext2
-rw-r--r-- 1 vmuser vmuser 6.7M Apr  7 13:48 output/images/rootfs.tar
-rw-r--r-- 1 vmuser vmuser 2.7M Apr  7 13:48 output/images/rootfs.tar.bz2
-rw-r--r-- 1 vmuser vmuser 403K Apr  7 13:34 output/images/u-boot.imx
-rw-r--r-- 1 vmuser vmuser 5.3M Apr  7 13:46 output/images/zImage

4. Config display as HMDI

1) Enter u-boot console
2) 
=> setenv mmcargs 'setenv bootargs console=${console},${baudrate} ${smp} root=${mmcroot} rootwait rw video=mxcfb0:dev=hdmi,1920x1080M@60,if=RGB24'
=> saveenv

5. Config display as single LVDS

6. Config display as dual LVDS