get panic in configure DDR to 2G BYTE

Dear SIR
We use omap4470 and 4AI.1.4P1 software.
We try to enable 2GByte DDR in our system.
system get panic when we configure to 2Gbyte.
EMIF register setting seem good and we can see following log in uboot.
----------------------------------------------------------
U-Boot 1.1.4 (Jun 22 2012 - 15:59:27)

Load address: 0x80e80000
DRAM: 2048 MB
Flash: 0 kB
In: serial
Out: serial
Err: serial
----------------------------------------------------

we do following change in kernel code.
1.omap4_ion.h //arch/arm/mach-omap2
#define PHYS_ADDR_SMC_MEM (0x80000000 + SZ_2G - PHYS_ADDR_SMC_SIZE)

2.blaze_defconfig.h
CONFIG_CMDLINE="console=ttyO2,115200n8 mem=2G vmalloc=768M androidboot.console=ttyO2 omap_wdt.timer_margin=30"

but system always panic log as below
-------------------------------------------------------------------------
CPU: ARMv7 Processor [412fc09a] revision 10 (ARMv7), cr=10c5387d
CPU: VIPT nonaliasing data cache, VIPT aliasing instruction cache
Machine: OMAP4 blaze board
*****TEST: size 0x2000000 addr0x0.
<6>Reserving 33554432 bytes SDRAM for VRAM
Memory policy: ECC disabled, Data cache writealloc
*****TEST: size 0x1000 addr0x0.
<0>Kernel panic - not syncing: ERROR: Failed to allocate 0x1000 bytes below 0x0.
--------------------------------------------------------------------------
kernel boot in 1Gbyte DDR setting is fine by modify blaze_defconfig.h
CONFIG_CMDLINE="console=ttyO2,115200n8 mem=1G vmalloc=768M androidboot.console=ttyO2 omap_wdt.timer_margin=30"

kernel panic only occur when we change to 2G setting
CONFIG_CMDLINE="console=ttyO2,115200n8 mem=2G vmalloc=768M androidboot.console=ttyO2 omap_wdt.timer_margin=30"

Please help:
1.Maybe DDR change from 1Gbyte to 2GByte need modify more code.Please adivce.
2.Where to configure system memory allocatioin table.
Thank you for taking the time to help.