These are the steps I follow in order to build a cross-compiler: 1) I build binutils for the target 2) I install the headers from a library (that is specific) 3) I build a minimal gcc for the target (only C language supported) 4) I build a library for the target (that is specific) 5) I build a full gcc for the target (C and C++ languages supported) For the step 2), it must be skipped for some targets: * If the target is avr, it must be skipped * If the target is i686-w64-mingw32, it must be done For the step 2) and 4), the library I use depends on the target: * If the target is avr, I use avr-libc [1] * If the target is i686-w64-mingw32, I use mingw-w64 [2] This method works fine for avr and i686-w64-mingw32, so I am wondering why it does not work for my armv6l-unknown-linux-gnueabihf machine too. I guess it is because I don't know which specific library I can use for the steps 2) and 4). Maybe newlib [3] is what I am looking for. Can you tell me if my method is correct and if newlib could be what I am looking for? Thank you. Best regards. [1] http://www.nongnu.org/avr-libc/ [2] http://mingw-w64.org/ [3] https://sourceware.org/newlib/ On Mon, 14 Mar 2016 10:21:53 +0000 Andrew Haley <aph@xxxxxxxxxx> wrote: > On 13/03/16 12:51, YuGiOhJCJ Mailing-List wrote: > >> On 13/03/16 05:01, YuGiOhJCJ Mailing-List wrote: > >>> 1) How we determine the correct machine name? > >> > >> It looks correct. > >> > > > > OK it is correct but how to know it is correct? > > Go to a Raspberry Pi and run config.guess. > > > I mean, I have chance to find people who have written articles where I can see the good machine name. > > But alone, it is hard to guess. > > I read [1] and it gives me the idea to use the config.guess script: > > $ scp /usr/share/automake-1.11/config.guess root@raspberrypi:~/ > > root@raspberrypi's password: > > config.guess 100% 44KB 43.8KB/s 00:00 > > $ ssh root@raspberrypi > > root@raspberrypi's password: > > Last login: Fri Jan 2 07:32:11 1970 from 192.168.0.6 > > Linux 4.1.19+. > > $ ./config.guess > > armv6l-unknown-linux-gnueabihf > > > > So, I think I could use this machine name too. > > I think you could too. > > > I don't like this solution with the config.guess script because it > > supposes to have an access to the target system in order to run the > > script on it. > > That's true. But you need access to the target system in order to be > able to test a cross compiler, so it's not a big issue. It's obvious > that you must be able to test a cross compiler after you build it. > > > Is there something (like a documentation) in the gcc source code > > that helps to guess the best machine name for an ARMv6 CPU on Linux? > > I don't think so. > > >>> 2) How to build my cross-compiler without glibc? > >> > >> Copy the root filesystem from a Raspberry Pi onto your machine, then > >> configure gcc with --sysroot=<dirname>, the RPi root filesystem. GCC > >> will then pull all target headers and libraries from the sysroot. > > > > I prefer a solution that does not require to have an access to the > > target machine. Also, I would like a solution that does not depend > > on binaries if that's possible. > > It's not: you need to be able to link against the target's libraries. > It's not just about libc: very few programs use only libc. This way, > you have all of the target's libraries and header files. > > > Why the method for a Raspberry Pi cross-compiler is so different > > from an i686-w64-mingw32 or avr cross-compiler please? > > It's the standard way for GNU/Linux cross-compilers. It's the best > way, and the easiest. The other ways are inferior. > > Andrew.
