MCUCR |= _BV(SRE) | _BV(SRW10);    // enable external memory (xram)
    XMCRA |= _BV(SRW01) | _BV(SRW00) | _BV(SRW11) | _BV(SRW10);
    XMCRB &= ~(_BV(XMM2) | _BV(XMM1) | _BV(XMM0));

AVR Memory Usage
----------------
Device: atmega128

Program:   42940 bytes (32.8% Full)
(.text + .data + .bootloader)

Data:       5282 bytes (129.0% Full)
(.data + .bss + .noinit)

EEPROM:       66 bytes (1.6% Full)
(.eeprom)

Build succeeded with 0 Warnings...

avr-gcc.exe -mmcu=atmega128 -Wl,-u,vfprintf -Wl,-Tdata=0x801100,--defsym=__heap_end=0x80ffff  -Wl,-Map=ppp.map at.o common.o fcs.o icmp.o ip.o main.o ppp.o tcp.o udp.o mmc.o logger.o time.o lcd.o ff.o    -lprintf_flt -lm  -o ppp.elf

u16 SRAM_Test(void)
{
    unsigned short j;

    Reset_WD();

    for (j = 0; j < RAM_SIZE; j++) {
        _SFR_MEM8(j + EXT_MEM_START) = (unsigned char)(j);
        Reset_WD();
    }
    for (j = 0; j < RAM_SIZE; j++)
    {
        if (_SFR_MEM8(j + EXT_MEM_START) != (unsigned char)(j)) return j;
        Reset_WD();
    }

   return 0xffff;            // past it's test
}

T_PPP            PPP;
....
memcpy_P((char*)&PPP.OUR_IP.ip32, OurIP, 4);
....

Memory Configuration

Name             Origin             Length             Attributes
text             0x00000000         0x00020000         xr
data             0x00800060         0x0000ffa0         rw !x
eeprom           0x00810000         0x00010000         rw !x
*default*        0x00000000         0xffffffff

Linker script and memory map

Address of section .data set to 0x800100
LOAD C:/WinAVR/bin/../lib/gcc/avr/3.4.6/../../../../avr/lib/avr5/crtm128.o
                0x0080ffff                __heap_end = 0x80ffff

.data           0x00800100       0xcc load address 0x0000a6f0
                0x00800100                PROVIDE (__data_start, .)
*(.data)
.data          0x00800100        0xc at.o
.data          0x0080010c       0x1a common.o
                0x00800110                MainBufferWr_Rx
                0x0080010c                rtc
.data          0x00800126       0x48 main.o
.data          0x0080016e       0x20 ppp.o
.data          0x0080018e        0x2 tcp.o
                0x0080018e                TCP_Socket
.data          0x00800190        0x1 mmc.o
.data          0x00800191       0x2d logger.o
.data          0x008001be        0xa ff.o
.data          0x008001c8        0x4 C:/WinAVR/bin/../lib/gcc/avr/3.4.6/../../../../avr/lib/avr5\libc.a(rand.o)
*(.gnu.linkonce.d*)
                0x008001cc                . = ALIGN (0x2)
                0x008001cc                _edata = .
                0x008001cc                PROVIDE (__data_end, .)

.bss            0x008001cc     0x13d6
                0x008001cc                PROVIDE (__bss_start, .)
*(.bss)
.bss           0x008001cc        0xc common.o
                0x008001d5                TimerIntCounter
                0x008001cd                UART0_RxBufferRd
                0x008001cf                UART1_RxBufferRd
                0x008001ce                UART0_RxBufferWr
                0x008001d7                LastResetReason
                0x008001d1                MainBufferWr_Tx
                0x008001d3                MainBufferRd_Rx
                0x008001cc                GPSModeSet
                0x008001d0                UART1_RxBufferWr
                0x008001d6                WatchdogCounter
.bss           0x008001d8        0x2 icmp.o
                0x008001d8                ICMP_Header
.bss           0x008001da        0x4 ppp.o
                0x008001da                CodeHeader
                0x008001dc                PPPHeader
.bss           0x008001de        0x4 tcp.o
                0x008001e0                TCP_TmpPort
                0x008001de                TCP_Header
.bss           0x008001e2        0x2 udp.o
                0x008001e2                UDP_Header
.bss           0x008001e4        0x2 mmc.o
.bss           0x008001e6      0x899 logger.o
.bss           0x00800a7f        0xc time.o
.bss           0x00800a8b        0x4 ff.o
*(COMMON)
COMMON         0x00800a8f        0x5 at.o
                0x00800a8f                AT
COMMON         0x00800a94      0x642 common.o
....

И ещё далее по тексту вот так:[code]
.data           0x00800100       0xcc load address 0x0000a6f0
                0x00800100                PROVIDE (__data_start, .)
*(.data)
.data          0x00800100        0xc at.o
.data          0x0080010c       0x1a common.o
    ....

## Linker flags
LDFLAGS = $(COMMON)
LDFLAGS += -Wl,-u,vfprintf -Wl,-Map=ppp.map
LDFLAGS += -Wl,-section-start=.data=0x801100,--defsym=__heap_end=0x80ffff

Linker script and memory map

Address of section .data set to 0x800100
LOAD C:/WinAVR/bin/../lib/gcc/avr/3.4.6/../../../../avr/lib/avr5/crtm128.o
Address of section .data set to 0x801100
                0x0080ffff                __heap_end = 0x80ffff

....

.data           0x00801100       0xd0 load address 0x0000abb0
                0x00801100                PROVIDE (__data_start, .)
*(.data)
.data          0x00801100        0xc at.o
.data          0x0080110c       0x1a common.o

unsigned char str[]="Test";