# Target definition: architecture, optimisations, etc... menu "Target options" comment "General target options" choice bool prompt "Target architecture:" default ARCH_x86 config ARCH_ARM bool prompt "arm" config ARCH_MIPS bool prompt "mips" config ARCH_x86 bool prompt "x86" config ARCH_x86_64 bool prompt "x86_64" endchoice choice bool prompt "Endianness:" config ARCH_BE bool prompt "Big endian" config ARCH_LE bool prompt "Little endian" endchoice comment "Target optimisations" config ARCH_CPU string prompt "Emit assembly for CPU" default "" help This specifies the name of the target ARM processor. GCC uses this name to determine what kind of instructions it can emit when generating assembly code. Pick a value from the gcc manual for your choosen gcc version and your target CPU. Leave blank if you don't know, or if your target architecture does not offer this option. config ARCH_TUNE string prompt "Tune for CPU" default "" help This option is very similar to the ARCH_CPU option (above), except that instead of specifying the actual target processor type, and hence restricting which instructions can be used, it specifies that GCC should tune the performance of the code as if the target were of the type specified in this option, but still choosing the instructions that it will generate based on the cpu specified by the ARCH_CPU option (above), or a (command-line) -mcpu= option. Pick a value from the gcc manual for your choosen gcc version and your target CPU. Leave blank if you don't know, or if your target architecture does not offer this option. config ARCH_ARCH string prompt "Achitecture level" default "" help GCC uses this name to determine what kind of instructions it can emit when generating assembly code. This option can be used in conjunction with or instead of the ARCH_CPU option (above), or a (command-line) -mcpu= option. Pick a value from the gcc manual for your choosen gcc version and your target CPU. Leave blank if you don't know, or if your target architecture does not offer this option. config ARCH_FPU string prompt "Use FPU" default "" help On some targets (eg. ARM), you can specify the kind of FPU to emit code for. See below wether to actually emit FP opcodes, or to emulate them. Pick a value from the gcc manual for your choosen gcc version and your target CPU. Leave blank if you don't know, or if your target architecture does not offer this option. choice bool prompt "Floating point:" config ARCH_FLOAT_HW bool prompt "hardware (FPU)" help Emit hardware floating point opcodes. If you've got a processor with a FPU, then you want that. If your hardware has no FPU, you still can use HW floating point, but need to compile support for FPU emulation in your kernel. Needless to say that emulating the FPU is /slooowwwww/... One situation you'd want HW floating point without a FPU is if you get binary blobs from different vendors that are compiling this way and can't (don't wan't to) change. config ARCH_FLOAT_SW bool prompt "software" help Do not emit any hardware floating point opcode. If your processor has no FPU, then you most probably want this, as it is faster than emulating the FPU in the kernel. endchoice config ARCH_FLOAT_SW_LIBFLOAT bool prompt "Use libfloat" default n depends on ARCH_FLOAT_SW help For those targets upporting it, you can use libfloat for the software floating point emulation. Note that some versions of gcc have support code that supersedes libfloat, while others don't. Known version of gcc that don't have support code are versions prior to 3.0, and version above 4.0. You should check gcc before deciding to use libfloat. config TARGET_CFLAGS string prompt "Default target CFLAGS" default "" help Used to add specific options when compiling libraries of the toolchain, that will run on the target (eg. libc.so). Note that the options above for CPU, tune, arch and FPU will be automaticaly used. You don't need to specify them here. Leave blank if you don't know better. comment "Toolchain options" config USE_SYSROOT bool prompt "Use sysroot'ed toolchain" default y help Use the 'shinny new' sysroot feature of gcc: libraries split between prefix/target/sys-root/lib and prefix/target/sys-root/usr/lib You definitely want to say 'Y' here. Yes you do. I know you do. Say 'Y'. config SHARED_LIBS bool prompt "Build shared libraries" default y help Say 'y' here, unless you don't want shared libraries. You might not want shared librries if you're building for a target that don't support it (maybe some nommu targets, for example, or bare metal). config TARGET_MULTILIB bool # prompt "Enable 'multilib' support (EXPERIMENTAL)" default n help Enable the so-called 'multilib' support. With the same toolchain, and on some architectures, you will be able to build big and little endian binaries, soft- and hard-float, etc... See the gcc configure manual at http://gcc.gnu.org/install/configure.html to see what multilib your target supports. It's preferable for now to build two (or more) toolchains, one for each configuration you need to support (eg. one for thumb and one for ARM, etc...). You can use the vendor string to diferentiate those toolchains. config TARGET_VENDOR string prompt "Vendor string" default "unknown" help Vendor part of the machine triplet. A triplet is of the form arch-vendor-kernel-system. You can set the second part, vendor, to whatever you see fit. Use a single word, or use underscores "_" to separate words. Keep the default (unkown) if you don't know better. config TARGET_ALIAS string prompt "Target alias" default "" help Normaly, you'd call your toolchain component (especially gcc) by prefixing the target triplet followed by a dash and the component name (eg. armeb-unknown-linux-uclibc-gcc). You can enter a shortcut here. This string will be used to create symbolic links to the toolchain tools (eg. if you enter "foo-bar" here, then gcc for your toolchain will also be available as "foo-bar-gcc" along with the original name). You shouldn't need to enter anything here, unless you plan to manually call the tools (autotools-based ./configure will use the standard name). config ARCH string default "arm" if ARCH_ARM default "mips" if ARCH_MIPS default "x86" if ARCH_x86 default "x86_64" if ARCH_x86_64 config BUILD string prompt "Build system triplet" default "" help Canonical name of the machine building the toolchain. You should leave empty, unless you really now what you're doing. config CC_NATIVE string prompt "Native gcc" default "gcc" help The native C compiler. You can set this to an alternative compiler if you have more than one installed (eg. gcc is gcc-4.1.1 and you want to use gcc-3.4.6). You can leave this empty as well, in which case gcc will be used. config CANADIAN bool prompt "Canadian build (EXPERIMENTAL)" default n help A canadian build allows to build a compiler on a first machine (build system), that will run on second machine (host system), targetting a third machine (target system). An example where you'd want a candian cross-compiler is to create a native compiler for your target. In this case host and target are the same. config HOST string prompt "Host system triplet" default "" depends on CANADIAN help Canonical name of the machine serving as host. config HOST_CC string prompt "Host system compiler" default "${CT_HOST}-" depends on CANADIAN help C compiler targeting the host system. If HOST_CC ends with a dash (-), then it is considered to be the prefix to gcc (eg. x86-pc-linuc-gnu-). If it is empty, it is formed by appending '-gcc' to HOST. Else it is considered to be the complete name of the compiler, with full path, or without path (provided that it can be found in PATH). endmenu