There are lot posts on this problem in google, but I have tried all the solutions but they are not working for me, so I'm posting here I am working with AT91BootStarp 3.5.9 with linux kernel 3.6.9. My problem is that Linux does not use the second memory bank (128 MB on EBI_CS1 mapped at 0x20000000).The memory mapping is as follows:0x70000000 => 0xc0000000 (128 MB - DDRSDRC0) 0x20000000 => 0xc8000000 (128 MB - EBI_CS1)As per ATMEL evaluation (user) board.While booting I see this message: Ignoring RAM at 70000000-77ffffff (vmalloc region overlap).I have enabled SparseMem and also tried patches posted at:http://blog.linuxconsulting.ro/2010/05/ ... -with.htmlI have checked & verified my DDR2 initializations in AT91Bootstrap and I dont see any issues at Bootstrap. Tested both memory banks, dont see any issues.I have added uBoot boot args as:mem= mem=128M@0x20000000 mem=128M@0x70000000 console=ttyS0,115200 root=/dev/mmcblk0p2 rw rootdelay=2 rootwait=1When I boot, I am getting following warning and board is getting configured with 128 MB not with 256 MB.Ignoring RAM at 70000000-77ffffff (vmalloc region overlap).CPU: ARM926EJ-S [41069265] revision 5 (ARMv5TEJ), cr=00053177CPU: VIVT data cache, VIVT instruction cacheMachine: Atmel AT91SAM9M10G45-EKIgnoring RAM at 70000000-77ffffff (vmalloc region overlap).Memory policy: ECC disabled, Data cache writebackAT91: Detected soc type: at91sam9g45AT91: Detected soc subtype: UnknownAT91: sram at 0x300000 of 0x10000 mapped at 0xfef68000Clocks: CPU 400 MHz, master 133 MHz, main 12.000 MHzBuilt 1 zonelists in Zone order, mobility grouping on.  Total pages: 32512Kernel command line: mem=128M@0x20000000 mem=128M@0x70000000 console=ttyS0,115200 root=/dev/mmcblk0p2 rw rootdelay=2 rootwait=1PID hash table entries: 512 (order: -1, 2048 bytes)Dentry cache hash table entries: 16384 (order: 4, 65536 bytes)Inode-cache hash table entries: 8192 (order: 3, 32768 bytes)Memory: 128MB = 128MB totalMemory: 124424k/124424k available, 6648k reserved, 0K highmemVirtual kernel memory layout:    vector  : 0xffff0000 - 0xffff1000   (   4 kB)    fixmap  : 0xfff00000 - 0xfffe0000   ( 896 kB)    vmalloc : 0xc8800000 - 0xff000000   ( 872 MB)    lowmem  : 0xc0000000 - 0xc8000000   ( 128 MB)    modules : 0xbf000000 - 0xc0000000   (  16 MB)      .text : 0xc0008000 - 0xc04d5f18   (4920 kB)      .init : 0xc04d6000 - 0xc050022c   ( 169 kB)      .data : 0xc0502000 - 0xc05345a0   ( 202 kB)       .bss : 0xc05345c4 - 0xc055711c   ( 139 kB)NR_IRQS:16 nr_irqs:16 16AT91: 160 gpio irqs in 5 bankssched_clock: 32 bits at 100 Hz, resolution 10000000ns, wraps every 4294967286msConsole: colour dummy device 80x30
Using two memory controllers with SPARSE_MEM on AT91SAM9G45
linux kernel;boot loader;arm