How to select build architecture with SCons - scons

I started with SCons yesterday but I encountered a problem while trying to convert my project from Premake to SCons. I didn't find how to change build architecture. If I don't set anything, SCons will compile the project for x86 architecture but I would like to have an option to compile my project to x64 and to ARM architectures. Also I want my project to be cross-platform/cross-compiler so I would like to avoid any compiler specific flags like gcc's -m64. Is there anyway of doing so?

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How do I build a newlib RISC-V toolchain with a modified linker script?

I'm trying to build a GCC/newlib cross compilation toolchain targeting an embedded OS on RISC-V. For this purpose, I need to modify the virtual addresses that binaries are linked at.
One way to achieve this is to modify the default linker script that ships with the toolchain.
I'm trying to find the best location in the involved components (newlib, binutils, gcc) where I can tweak the default linker script that is shipped with the toolchain.
For some platforms, newlib already provides partial or complete linker scripts. It seems for RISC-V the default linker script produced by binutils is used.
I'm fine with patching binutils, but I can't find how the RISC-V linker script is actually built or how I would modify anything in it. Any pointers are appreciated!
The different linker scripts for riscv are build from :
binutils/ld/scripttempl/elf.sc
binutils/ld/emulparams/elf32lriscv*
binutils/ld/emulparams/elf64lriscv*
You will need to modifiy these files or create your own and modify the Makefiles.

Clang huge compilation?

Good Morning.
I am compiling Clang, following the instructions here Getting Started: Building and Running Clang
I am on linux and the compilation goes smoothly. But I think I am missing out something...
I want to compile ONLY clang, not all the related libraries. The option -DLLVM_ENABLE_PROJECTS=clang seems doing what I want (check LLVM_ENABLE_PROJECTS here)
If I use the instructions written there, I can compile, but I think I am compiling too much....a build directory of 70GB seems too much to me...
I tried to download the official debian source and compile the debian package (same source code! just using the "debian way" to create a package from official debian source), just to compare...The compilation goes smoothly, is very fast, and the build directory is much much smaller...as I expected...
I noticed in the first link I provided the phrase "This builds both LLVM and Clang for debug mode."...
So, anyone knows if my problem is due to the fact that I am compiling a "debug mode" version? if so, how could I compile the default version? and is there a way to compile ONLY clang without LLVM?
Yes, debug mode binaries are typically much larger than release mode binaries.
Cmake normally uses CMAKE_BUILD_TYPE to determine he build type. It can be set from the command line with -DCMAKE_BUILD_TYPE="Release" o -DCMAKE_BUILD_TYPE="Debug" (sometimes there are other build types as well).

Is there any way to add arm compiler to Scons Toolchain?

I tried by adding it using :
--tc=gcc and also using --target=arm
it looks like scons do not support it.
Im not using sbuild Im using parts and Im looking for way to to compile my program with arm-linux-gnueabi-gcc when running scons --tc=gcc --target=arm currently I get an error that it cannot find gcc on target posix-arm
is there any way to change the default compiler of scons if the compiler is not included in scons Tools directory using parts?
Thank you

Input/output error using Android ndk-build

Using Android NDK R10E, I am trying to build a shared library for all supported ABI's and I am getting the following error for some but not all ABI's:
[armeabi] SharedLibrary : libMyLib.so /home/user/android-ndk-r10e/toolchains/arm-linux-androideabi-4.8/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.8/../../../../arm-linux-androideabi/bin/ld:
fatal error: /home/user/source/MyLib/obj/local/armeabi/libMyLib.so: Input/output error
The project successfully builds for arm64-v8a, mips and mips64 but fails with the above error for armeabi, armeabi-v7a, x86 and x86_64.
I have a static library project and another shared library project and they both build successfully for all 7 ABI's.
If I compare the contents of obj/local/ for an ABI that builds and one that does not, they both contain all the same files except for libMyLib.so.
The difference between those two sets of ABIs is that the failing ones link using ld.gold and the working ones use ld.bfd.
Two things to try:
Use the 4.9 toolchain. It hopefully has the bug fix.
If that doesn't work, you can add -fuse-ld=bfd to your ldflags to use bfd even on the architectures that default to gold.
Same issue happened to me in r15c.
The fix was to copy
android-ndk-r15c/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/arm-linux-androideabi/bin/ld.bfd over ld.
I had to copy it because I could not easily find a way to specify this flag to CMake to use it while detecting the compiler features.

crosscompile glibc for arm

Good day
Currently, I'm working on an embedded device based on arm-linux. I want to build GCC for my target architecture with Glibc. GCC builds successful, but I have trouble with Glibc build.
I use the latest version of Glibc (ftp.gnu.org/gnu/glibc/glibc-2.12.1.tar.gz) and port for them (ftp.gnu.org/gnu/glibc/glibc-ports-2.12.1.tar.gz)
my configuration line:
../../glibc-2.12.1/configure --host=arm-none-linux-gnueabi --prefix=/home/anatoly/Desktop/ARM/build/glibc-build --enable-add-ons --with-binutils=/home/anatoly/Desctop/ARM/toolchain/arm/bin/
configuration script work fine, but i get some compile error:
...
/home/anatoly/Desktop/ARM/src/glibc-2.12.1/malloc/libmemusage_pic.a(memusage.os): In function me':
/home/anatoly/Desktop/ARM/src/glibc-2.12.1/malloc/lmemusage.c:253: undefined reference to__eabi+read_tp'
...
I also tried using the old version (2.11, 2.10) but have the same error.
Does anybody know the solution for this problem?
Use a precompiled toolchain, like those provided by code sourcery.
If you want to make your own, optimised (premature optimization is the root of all evil), use crosstool-NG, which is a tool dedicated to cross-compilation toolchain building.
If you are not convinced, and want to do everything with your own hands, ask your question on the crosstool-NG mailing list.
Try substituting arm-linux-gnueabi for arm-none-linux-gnueabi. Check that a compiler, loader etc. with the prefix you used for "host" exist on your path.

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