[Samsung Galaxy R i9103] UnknownzD:
So this is a major news for devs, if you found your AOSP / CM build doesn't work, make sure that you have the following line enabled if you are using TARGET_ARCH_VARIANT := armv7-a :

TARGET_ARCH_VARIANT_FPU := vfpv3-d16

This is due to a bug in armv7-a.mk in CM repo that automatically set FPU to neno for no reason. (btw, I have already reported the bug, so lets see it get patched or not later)

btw DO NOT change the line of TARGET_ARCH_VARIANT_FPU to vfpv3, otherwise your CM / AOSP build will not boot @ all.

The following BoardConfig.mk is used for compiling CWM on my kernels. And it is working for compiling CWM on my machine. You can edit the line such as USE_CAMERA_STUB, TARGET_NO_RADIOIMAGE or TARGET_PREBUILT_KERNEL on your own. However do not edit the line since TARGET_CPU_ABI to BOARD_FLASH_BLOCK_SIZE as they are vital and already right for our I9103.

LOCAL_PATH := $(call my-dir)
#USE_CAMERA_STUB := true

# inherit from the proprietary version
-include vendor/samsung/I9103/BoardConfigVendor.mk

TARGET_CPU_ABI := armeabi-v7a
TARGET_CPU_ABI2 := armeabi
TARGET_ARCH_VARIANT := armv7-a
TARGET_ARCH_VARIANT_CPU := cortex-a9
# DO NOT change the following line to vfpv3 as it is not really supported on our device!
TARGET_ARCH_VARIANT_FPU := vfpv3-d16
TARGET_CPU_SMP := true
ARCH_ARM_HAVE_TLS_REGISTER := true
TARGET_HAVE_TEGRA_ERRATA_657451 := true
TARGET_BOARD_PLATFORM := tegra
TARGET_BOARD_PLATFORM_GPU := tegra # Useless for CM7 build
TARGET_BOOTLOADER_BOARD_NAME := n1
TARGET_USERIMAGES_USE_EXT4 := true

BOARD_KERNEL_CMDLINE :=
BOARD_KERNEL_BASE := 0x10000000
BOARD_KERNEL_PAGESIZE := 2048

# fix this up by examining /proc/mtd on a running device
# Boot image size is 16384 x 512 bytes = 8388608
# You can double check it with fdisk -l /dev/block/mmcblk0p8
BOARD_BOOTIMAGE_PARTITION_SIZE := 0x00800000
# Recovery image size is 10240 x 512 bytes = 5242880
# You can double check it with fdisk -l /dev/block/mmcblk0p8
BOARD_RECOVERYIMAGE_PARTITION_SIZE := 0x00500000
# System image size is 1228800 x 512 bytes = 629145600
# You can double check it with fdisk -l /dev/block/mmcblk0p2
BOARD_SYSTEMIMAGE_PARTITION_SIZE := 0x25800000
# User data image size is 4194304 x 512 bytes = 2147483648
# You can double check it with fdisk -l /dev/block/mmcblk0p6
BOARD_USERDATAIMAGE_PARTITION_SIZE := 0x80000000
BOARD_FLASH_BLOCK_SIZE := 2048

TARGET_PREBUILT_KERNEL := device/samsung/I9103/kernel

TARGET_NO_KERNEL := false
TARGET_NO_RECOVERY := false
TARGET_NO_BOOTLOADER := true
TARGET_NO_RADIOIMAGE := true

BOARD_HAS_NO_SELECT_BUTTON := true
# Use this flag if the board has a ext4 partition larger than 2gb
BOARD_HAS_LARGE_FILESYSTEM := true

btw I have an updated version of armv7-a.mk so that it should work on any device using armv7-a even when FPU is not defined. If your toolchain is complaing errors like the switch -mcpu is not working with -march, just remove the -mcpu switch on your own.

# Configuration for Linux on ARM.
# Generating binaries for the ARMv7-a architecture and higher
#
ARCH_ARM_HAVE_THUMB_SUPPORT := true
ARCH_ARM_HAVE_FAST_INTERWORKING := true
ARCH_ARM_HAVE_64BIT_DATA := true
ARCH_ARM_HAVE_HALFWORD_MULTIPLY := true
ARCH_ARM_HAVE_CLZ := true
ARCH_ARM_HAVE_FFS := true
ARCH_ARM_HAVE_ARMV7A := true

ifeq ($(strip $(TARGET_ARCH_VARIANT_FPU)),)
ARCH_ARM_HAVE_VFP := false
else
ARCH_ARM_HAVE_VFP := true
endif

ifeq ($(strip $(TARGET_ARCH_VARIANT_FPU)),neon)
ARCH_ARM_HAVE_NEON := true
endif

ifeq ($(strip $(TARGET_CPU_SMP)),true)
ARCH_ARM_HAVE_TLS_REGISTER := true
endif

arch_variant_cflags := \
-march=armv7-a \
-mtune=$(strip $(TARGET_ARCH_VARIANT_CPU)) \
-mcpu=$(strip $(TARGET_ARCH_VARIANT_CPU)) \
-D__ARM_ARCH_7__ \
-D__ARM_ARCH_7A__

ifeq ($(strip $(ARCH_ARM_HAVE_VFP)),true)
ifeq ($(strip $(ARCH_ARM_HAVE_NEON)),true)
arch_variant_cflags += -D__ARM_NEON__ -D__ARM_HAVE_NEON
else
arch_variant_cflags += -D__VFP_FP__ -D__ARM_HAVE_VFP
endif
arch_variant_cflags += -mfloat-abi=softfp -mfpu=$(strip $(TARGET_ARCH_VARIANT_FPU))
else
arch_variant_cflags += -mfloat-abi=soft
endif

ifeq ($(strip $(TARGET_ARCH_VARIANT_CPU)),cortex-a8)
arch_variant_ldflags := \
-Wl,--fix-cortex-a8
else
arch_variant_ldflags :=
endif

In addition, please look at the required errata for building stuffs on our device.

As our device is using an epic old ARM cpu, it means that it may have errata inside. Errata means errors on the hardware that cannot be fixed, however can be bypassed with errata patch.

In conjunction with finding the required errata patch, this is our cpuinfo

cat /proc/cpuinfo

Processor : ARMv7 Processor rev 0 (v7l)

processor : 0

BogoMIPS : 999.42

processor : 1

BogoMIPS : 999.42

Features : swp half thumb fastmult vfp edsp vfpv3 vfpv3d16

CPU implementer : 0x41

CPU architecture: 7

CPU variant : 0x1

CPU part : 0xc09

CPU revision : 0

Hardware : n1

Revision : 000d

Serial : 304d11d0943807ae

So next time when you try to make a custom kernel or port a kernel to this device, keep an eye on those errata please. Nvidia git sometimes made patch for those erratas as well.

For example, TARGET_HAVE_TEGRA_ERRATA_657451 is a config value telling that the src code to enable errata #657451 patch for our device. (And I have enabled that in our BoardConfig.mk already.)