Hi All, After downloading linaro toolchain by apt-get in ubuntu, I compiled the uboot for ARM1136 SoC with -march=armv5 option. And it can compile successfully. Then I let the uboot run on target boards and system failed due to "undefined instructions". Checked linaro toolchain options, it is:
#arm-linux-gnueabi-gcc -v Using built-in specs. COLLECT_GCC=arm-linux-gnueabi-gcc COLLECT_LTO_WRAPPER=/usr/lib/gcc/arm-linux-gnueabi/4.5.2/lto-wrapper Target: arm-linux-gnueabi Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.5.2-5ubuntu2~ppa1' --with-bugurl=file:///usr/share/doc/gcc-4.5/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.5 --enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/arm-linux-gnueabi/include/c++/4.5.2 --libdir=/usr/lib --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-plugin --enable-gold --enable-ld=default --with-plugin-ld=ld.gold --enable-objc-gc --disable-sjlj-exceptions --with-arch=armv7-a --with-float=softfp --with-fpu=vfpv3-d16 --with-mode=thumb --disable-werror --enable-checking=release --program-prefix=arm-linux-gnueabi- --includedir=/usr/arm-linux-gnueabi/include --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=arm-linux-gnueabi --with-headers=/usr/arm-linux-gnueabi/include --with-libs=/usr/arm-linux-gnueabi/lib Thread model: posix gcc version 4.5.2 (Ubuntu/Linaro 4.5.2-5ubuntu2~ppa1)
The imporant options are "--with-arch=armv7-a --with-float=softfp --with-fpu=vfpv3-d16". I just want to ask whether these options stop arm-linux-gnueabi-gcc to support old arch? If so, according to gcc documents at http://gcc.gnu.org/install/configure.html,
"
--with-cpu=cpu --with-cpu-32=cpu --with-cpu-64=cpu Specify which cpu variant the compiler should generate code for by default. cpu will be used as the default value of the -mcpu= switch. This option is only supported on some targets, including ARM, i386, M68k, PowerPC, and SPARC. The --with-cpu-32 and --with-cpu-64 options specify separate default CPUs for 32-bit and 64-bit modes; these options are only supported for i386, x86-64 and PowerPC. --with-schedule=cpu --with-arch=cpu --with-arch-32=cpu --with-arch-64=cpu --with-tune=cpu --with-tune-32=cpu --with-tune-64=cpu --with-abi=abi --with-fpu=type --with-float=type These configure options provide default values for the -mschedule=, -march=, -mtune=, -mabi=, and -mfpu= options and for -mhard-float or -msoft-float. As with --with-cpu, which switches will be accepted and acceptable values of the arguments depend on the target. "
There are only default values for later compiling. Users should be able to swith to other values by setting other options. But why did arm-linux-gnueabi-gcc still build "undefined instructions" to arm1136 with "arch=armv5"? In fact arm1136 is armv6.
Then i compiled a toolchain for linaro gcc-linaro-4.4-2011.02-0 codes by myself, the options are simple:
#arm-none-linux-gnueabi-gcc -v Using built-in specs. Target: arm-none-linux-gnueabi Configured with: ../gcc-linaro-4.4-2011.02-0/configure --target=arm-none-linux-gnueabi --prefix=/home/vmuser/development/toolchain/build-toolchain/tools --enable-languages=c,c++ --disable-libgomp Thread model: posix gcc version 4.4.5 (Linaro GCC 4.4-2011.02-0)
Then I compiled uboot by this toolchain again, the uboot can work. Then why can the toolchain compiled by myself support more arch? And what performance is lost in my compiling?
Thanks Barry