ARM-gcc编译器放到外部的nor flash中脚本应该如何编写呢

我使用LPC1788处理器，因为程序比较大，所以打算将一部分程序烧写到外部的nor flash中，MDK下添加了nor flash的烧写算法，而且测试也已经通过并可以烧写程序，程序可正常运行。keil的链接脚本比较简单，而且生成方便。
因为用到了一些标准库以及.a的静态库，所以使用gnu的工具链，但是链接脚本不会编写，求指教，外部nor flash起始地址为0x90000000，MEMORY段已经标识，比如放一个lib.a和一个hello.o到外部的nor flash中 脚本应该如何编写
原链接脚本如下：
* linker script for LPC1788 (512kB Flash, 48kB + 48kB SRAM ) with GNU ld
* yiyue.fang 2012-04-14
*/
/* Program Entry, set to mark it as "used" and avoid gc */
MEMORY
{
CODE (rx) : ORIGIN = 0x00000000, LENGTH = 0x00080000
DATA (rw) : ORIGIN = 0x10000000, LENGTH = 0x00010000
EXCODE (rx) : ORIGIN = 0x90000000, LENGTH = 0x00400000
}
ENTRY(Reset_Handler)
_system_stack_size = 0x200;
SECtiONS
{
.text :
{
. = ALIGN(4);
KEEP(*(.isr_vector)) /* Startup code */
. = ALIGN(4);
*(.text) /* remaining code */
*(.text.*) /* remaining code */
*(.rodata) /* read-only data (constants) */
*(.rodata*)
*(.glue_7)
*(.glue_7t)
*(.gnu.linkonce.t*)
/* section information for finsh shell */
. = ALIGN(4);
__fsymtab_start = .;
KEEP(*(FSymTab))
__fsymtab_end = .;
. = ALIGN(4);
__vsymtab_start = .;
KEEP(*(VSymTab))
__vsymtab_end = .;
. = ALIGN(4);
. = ALIGN(4);
_etext = .;
} > CODE = 0
/* .ARM.exidx is sorted, so has to go in its own output section. */
__exidx_start = .;
.ARM.exidx :
{
*(.ARM.exidx* .gnu.linkonce.armexidx.*)
/* This is used by the startup in order to initialize the .data secion */
_sidata = .;
} > CODE
__exidx_end = .;
/* .data section which is used for initialized data */
.data : AT (_sidata)
{
. = ALIGN(4);
/* This is used by the startup in order to initialize the .data secion */
_sdata = . ;
*(.data)
*(.data.*)
*(.gnu.linkonce.d*)
. = ALIGN(4);
/* This is used by the startup in order to initialize the .data secion */
_edata = . ;
} >DATA
.stack :
{
. = . + _system_stack_size;
. = ALIGN(4);
_estack = .;
} >DATA
__bss_start = .;
.bss :
{
. = ALIGN(4);
/* This is used by the startup in order to initialize the .bss secion */
_sbss = .;
*(.bss)
*(.bss.*)
*(COMMON)
. = ALIGN(4);
/* This is used by the startup in order to initialize the .bss secion */
_ebss = . ;
*(.bss.init)
} > DATA
__bss_end = .;
_end = .;
/* Stabs debugging sections. */
.stab 0 : { *(.stab) }
.stabstr 0 : { *(.stabstr) }
.stab.excl 0 : { *(.stab.excl) }
.stab.exclstr 0 : { *(.stab.exclstr) }
.stab.index 0 : { *(.stab.index) }
.stab.indexstr 0 : { *(.stab.indexstr) }
.comment 0 : { *(.comment) }
/* DWARF debug sections.
* Symbols in the DWARF debugging sections are relative to the beginning
* of the section so we begin them at 0. */
/* DWARF 1 */
.debug 0 : { *(.debug) }
.line 0 : { *(.line) }
/* GNU DWARF 1 extensions */
.debug_srcinfo 0 : { *(.debug_srcinfo) }
.debug_sfnames 0 : { *(.debug_sfnames) }
/* DWARF 1.1 and DWARF 2 */
.debug_aranges 0 : { *(.debug_aranges) }
.debug_pubnames 0 : { *(.debug_pubnames) }
/* DWARF 2 */
.debug_info 0 : { *(.debug_info .gnu.linkonce.wi.*) }
.debug_abbrev 0 : { *(.debug_abbrev) }
.debug_line 0 : { *(.debug_line) }
.debug_frame 0 : { *(.debug_frame) }
.debug_str 0 : { *(.debug_str) }
.debug_loc 0 : { *(.debug_loc) }
.debug_macinfo 0 : { *(.debug_macinfo) }
/* SGI/MIPS DWARF 2 extensions */
.debug_weaknames 0 : { *(.debug_weaknames) }
.debug_funcnames 0 : { *(.debug_funcnames) }
.debug_typenames 0 : { *(.debug_typenames) }
.debug_varnames 0 : { *(.debug_varnames) }
}