[SOLVED] [ARM]linuxrc (1): undefined instruction

i build busybox with gcc options:

-march=armv4t -mcpu=arm920t -msoft-float -mno-thumb-interwork

of course ,it is compiled successfully.
i mouted the rootfs via nfs,kernel starts up ok,while start the linuxrc , it shows follow:

Freeing init memory: 132K
linuxrc (1): undefined instruction: pc=00063350
Code: e12fff1e 03a00001 13a00000 e12fff1e (e16f2f11) 
s3c24xx_serial_stop_rx: port=c0414fec
Kernel panic - not syncing: Attempted to kill init!
[<c00388c0>] (unwind_backtrace+0x0/0xe4) from [<c03025e8>] (panic+0x50/0x178)
[<c03025e8>] (panic+0x50/0x178) from [<c0047d5c>] (do_exit+0xa8/0x620)
[<c0047d5c>] (do_exit+0xa8/0x620) from [<c00485ac>] (do_group_exit+0x88/0xb8)
[<c00485ac>] (do_group_exit+0x88/0xb8) from [<c0051c84>] (get_signal_to_deliver+0x2f0/0x328)
[<c0051c84>] (get_signal_to_deliver+0x2f0/0x328) from [<c0035870>] (do_signal+0xb0/0x5b8)
[<c0035870>] (do_signal+0xb0/0x5b8) from [<c003621c>] (do_notify_resume+0x14/0x5c)
[<c003621c>] (do_notify_resume+0x14/0x5c) from [<c0033654>] (work_pending+0x24/0x28)

after disassembling the linuxrc , e12fff1e is instructon is:

bx lr

03a00001 is movne
13a00000 is movnq

the armv4t(arm920t) should support this instruction, so any help?

gcc toolchain verbose:

Using built-in specs.
COLLECT_GCC=arm-none-linux-gnueabi-gcc
COLLECT_LTO_WRAPPER=/media/DISK_H/LINUXW/arm2440_dev/tools/bin/../libexec/gcc/arm-none-linux-gnueabi/4.5.4/lto-wrapper
Target: arm-none-linux-gnueabi
Configured with: ../gcc-4.5.4/configure --prefix=/myex/arm2440_dev/tools --target=arm-none-linux-gnueabi --enable-languages=c,c++ --disable-nls
Thread model: posix
gcc version 4.5.4 (GCC)

gcc toochain specs:

*asm:
%{mbig-endian:-EB} %{mlittle-endian:-EL} %{mcpu=*:-mcpu=%*} %{march=*:-march=%*} %{mapcs-*:-mapcs-%*} %(subtarget_asm_float_spec) %{mthumb-interwork:-mthumb-interwork} %{msoft-float:-mfloat-abi=soft} %{mhard-float:-mfloat-abi=hard} %{mfloat-abi=*} %{mfpu=*} %(subtarget_extra_asm_spec)

*asm_debug:
%{!g0:%{gstabs*:--gstabs}%{!gstabs*:%{g*:--gdwarf2}}} %{fdebug-prefix-map=*:--debug-prefix-map %*}

*asm_final:


*asm_options:
%{--target-help:%:print-asm-header()} %a %Y %{c:%W{o*}%{!o*:-o %w%b%O}}%{!c:-o %d%w%u%O}

*invoke_as:
%{!fwpa:   %{fcompare-debug=*|fdump-final-insns=*:%:compare-debug-dump-opt()}   %{!S:-o %|.s |
 as %(asm_options) %m.s %A }  }

*cpp:
%(subtarget_cpp_spec)					%{msoft-float:%{mhard-float:							%e-msoft-float and -mhard_float may not be used together}}	%{mbig-endian:%{mlittle-endian:		%e-mbig-endian and -mlittle-endian may not be used together}}

*cpp_options:
%(cpp_unique_options) %1 %{m*} %{std*&ansi&trigraphs} %{W*&pedantic*} %{w} %{f*} %{g*:%{!g0:%{g*} %{!fno-working-directory:-fworking-directory}}} %{O*} %{undef} %{save-temps*:-fpch-preprocess}

*cpp_debug_options:
%{d*}

*cpp_unique_options:
%{C|CC:%{!E:%eGCC does not support -C or -CC without -E}} %{!Q:-quiet} %{nostdinc*} %{C} %{CC} %{v} %{I*&F*} %{P} %I %{MD:-MD %{!o:%b.d}%{o*:%.d%*}} %{MMD:-MMD %{!o:%b.d}%{o*:%.d%*}} %{M} %{MM} %{MF*} %{MG} %{MP} %{MQ*} %{MT*} %{!E:%{!M:%{!MM:%{!MT:%{!MQ:%{MD|MMD:%{o*:-MQ %*}}}}}}} %{remap} %{g3|ggdb3|gstabs3|gcoff3|gxcoff3|gvms3:-dD} %{H} %C %{D*&U*&A*} %{i*} %Z %i %{fmudflap:-D_MUDFLAP -include mf-runtime.h} %{fmudflapth:-D_MUDFLAP -D_MUDFLAPTH -include mf-runtime.h} %{E|M|MM:%W{o*}}

*trad_capable_cpp:
cc1 -E %{traditional|ftraditional|traditional-cpp:-traditional-cpp}

*cc1:
%{profile:-p}

*cc1_options:
%{pg:%{fomit-frame-pointer:%e-pg and -fomit-frame-pointer are incompatible}} %1 %{!Q:-quiet} %{!dumpbase:-dumpbase %B} %{d*} %{m*} %{a*} %{fcompare-debug-second:%:compare-debug-auxbase-opt(%b)}  %{!fcompare-debug-second:%{c|S:%{o*:-auxbase-strip %*}%{!o*:-auxbase %b}}}%{!c:%{!S:-auxbase %b}}  %{g*} %{O*} %{W*&pedantic*} %{w} %{std*&ansi&trigraphs} %{v:-version} %{pg:-p} %{p} %{f*} %{undef} %{Qn:-fno-ident} %{--help:--help} %{--target-help:--target-help} %{--help=*:--help=%(VALUE)} %{!fsyntax-only:%{S:%W{o*}%{!o*:-o %b.s}}} %{fsyntax-only:-o %j} %{-param*} %{fmudflap|fmudflapth:-fno-builtin -fno-merge-constants} %{coverage:-fprofile-arcs -ftest-coverage}

*cc1plus:


*link_gcc_c_sequence:
%{static:--start-group} %G %L %{static:--end-group}%{!static:%G}

*link_ssp:
%{fstack-protector|fstack-protector-all:-lssp_nonshared -lssp}

*endfile:
%{shared|pie:crtendS.o%s;:crtend.o%s} crtn.o%s

*link:
%{!static:--eh-frame-hdr} %{h*} %{version:-v}    %{b}    %{static:-Bstatic}    %{shared:-shared}    %{symbolic:-Bsymbolic}    %{rdynamic:-export-dynamic}    %{!dynamic-linker:-dynamic-linker %{muclibc:%{mglibc:%e-mglibc and -muclibc used together}/lib/ld-uClibc.so.0;:/lib/ld-linux.so.3}}    -X    %{mbig-endian:-EB} %{mlittle-endian:-EL} -m armelf_linux_eabi %{mbig-endian:%{march=armv7-a|mcpu=cortex-a5|mcpu=cortex-a8|mcpu=cortex-a9:%{!r:--be8}}}

*lib:
%{pthread:-lpthread}    %{shared:-lc}    %{!shared:%{profile:-lc_p}%{!profile:-lc}}

*mfwrap:
 %{static: %{fmudflap|fmudflapth:  --wrap=malloc --wrap=free --wrap=calloc --wrap=realloc --wrap=mmap --wrap=munmap --wrap=alloca} %{fmudflapth: --wrap=pthread_create}} %{fmudflap|fmudflapth: --wrap=main}

*mflib:
%{fmudflap|fmudflapth: -export-dynamic}

*link_gomp:


*libgcc:
%{static|static-libgcc:-lgcc -lgcc_eh}%{!static:%{!static-libgcc:%{!shared-libgcc:-lgcc --as-needed -lgcc_s --no-as-needed}%{shared-libgcc:-lgcc_s%{!shared: -lgcc}}}}

*startfile:
%{!shared: %{pg|p|profile:gcrt1.o%s;pie:Scrt1.o%s;:crt1.o%s}}    crti.o%s %{static:crtbeginT.o%s;shared|pie:crtbeginS.o%s;:crtbegin.o%s}

*switches_need_spaces:
o

*cross_compile:
1

*version:
4.5.4

*multilib:
. ;

*multilib_defaults:
marm mlittle-endian mhard-float mno-thumb-interwork

*multilib_extra:


*multilib_matches:


*multilib_exclusions:


*multilib_options:


*linker:
collect2

*linker_plugin_file:


*lto_wrapper:


*lto_gcc:


*lto_libgcc:


*link_libgcc:
%D

*md_exec_prefix:


*md_startfile_prefix:


*md_startfile_prefix_1:


*startfile_prefix_spec:


*sysroot_spec:
--sysroot=%R

*sysroot_suffix_spec:


*sysroot_hdrs_suffix_spec:


*subtarget_cpp_spec:
%{posix:-D_POSIX_SOURCE} %{pthread:-D_REENTRANT}

*subtarget_extra_asm_spec:
%{mabi=apcs-gnu|mabi=atpcs:-meabi=gnu;:-meabi=5} %{mcpu=arm8|mcpu=arm810|mcpu=strongarm*|march=armv4:--fix-v4bx}

*subtarget_asm_float_spec:
%{mapcs-float:-mfloat}

*link_command:
%{!fsyntax-only:%{!c:%{!M:%{!MM:%{!E:%{!S:    %(linker)     %{fuse-linker-plugin:     -plugin %(linker_plugin_file)     -plugin-opt=%(lto_wrapper)     -plugin-opt=%(lto_gcc)     %{static|static-libgcc:-plugin-opt=-pass-through=%(lto_libgcc)}	    %{static:-plugin-opt=-pass-through=-lc}	    %{O*:-plugin-opt=-O%*}     %{w:-plugin-opt=-w}     %{f*:-plugin-opt=-f%*}     %{m*:-plugin-opt=-m%*}     %{v:-plugin-opt=-v}     }     %{flto} %{fwhopr} %l %{pie:-pie} %X %{o*} %{A} %{d} %{e*} %{m} %{N} %{n} %{r}    %{s} %{t} %{u*} %{x} %{z} %{Z} %{!A:%{!nostdlib:%{!nostartfiles:%S}}}    %{static:} %{L*} %(mfwrap) %(link_libgcc) %o    %{fopenmp|ftree-parallelize-loops=*:%:include(libgomp.spec)%(link_gomp)} %(mflib)    %{fprofile-arcs|fprofile-generate*|coverage:-lgcov}    %{!nostdlib:%{!nodefaultlibs:%(link_ssp) %(link_gcc_c_sequence)}}    %{!A:%{!nostdlib:%{!nostartfiles:%E}}} %{T*} }}}}}}

I found that libgcc is built with cpu=arm10tdmi and arch=armv5t but the vmlinux built with this toolchain is armv4t.but why?
i wrote a hello world program by this toolchain with arch=armv4t , but it was compiled in armv5t.
I rebuild gcc toolchain with arch=armv4t and cpu=arm9tdmi, the linuxrc of busybox works ok. and other program that specify the arch=armv5t could be built ok with armv5t not armv4t.
Does the gcc has a mini support for the arch?