The toolchain that buildroot generates never compiles Dataflashboot-1.05. This is used on the AT91RM9200 to copy u-boot to SDRAM and jump to it. I tried different versions of buildroot from historic to current snapshot, the error occurs in all of them. Might be related to a software/hardware float issue.

/home/oliver/buildroot/output/staging/usr/bin/arm-linux-uclibcgnueabi-ld -T elf32-littlearm.lds -Ttext 0 -n -o DataflashBoot-1.05.out objs/cstartup_ram.o objs/at45.o objs/com.o objs/dataflash.o objs/div0.o objs/init.o objs/main.o objs/stdio.o objs/asm_isr.o objs/jump.o objs/_udivsi3.o objs/_umodsi3.o objs/led.o
objs/at45.o: In function `AT91F_DataFlashSendCommand':
at45.c:(.text+0xf0): undefined reference to `__aeabi_uidiv'
at45.c:(.text+0x104): undefined reference to `__aeabi_uidivmod'
objs/at45.o: In function `AT91F_PartialPageWrite':
at45.c:(.text+0x4a8): undefined reference to `__aeabi_uidiv'
at45.c:(.text+0x4f8): undefined reference to `__aeabi_uidivmod'
objs/at45.o: In function `AT91F_DataFlashWrite':
at45.c:(.text+0x5f4): undefined reference to `__aeabi_uidivmod'
at45.c:(.text+0x680): undefined reference to `__aeabi_uidiv'
objs/stdio.o: In function `number':
stdio.c:(.text+0x2a4): undefined reference to `__aeabi_uidiv'
stdio.c:(.text+0x2b8): undefined reference to `__aeabi_uidivmod'
make[1]: *** [DataflashBoot-1.05.out] Fehler 1
make[1]: leaving directory '/home/oliver/buildroot/output/build/DataflashBoot-1.05'
make: *** [/home/oliver/buildroot/output/build/DataflashBoot-1.05/DataflashBoot-1.05.bin] error 2