Memory requirements for building coreclr are unclear

[amanda-mitchell]

Building coreclr on Linux appears to require more than 512MB of RAM to be installed (which rules out a number of lightweight VMs that developers might use when getting started). Presently, this is not documented, and the error message when the system runs out of RAM is unhelpful.

Background

I attempted to build coreclr according to https://github.com/dotnet/coreclr/wiki/Linux-instructions

Since I'm on Windows, I installed Vagrant (with the default VirtualBox provider) and pulled down the ubuntu/trusty64 box and began to follow the build instructions. When I ran build.sh, I made it most of the way through the build, until I received the following error when trying to link libcoreclr.so:

Linking CXX shared library libcoreclr.so
clang: warning: argument unused during compilation: '-nostdinc++'
clang: error: linker command failed due to signal (use -v to see invocation)
make[2]: *** [src/dlls/mscoree/coreclr/libcoreclr.so] Error 254
make[1]: *** [src/dlls/mscoree/coreclr/CMakeFiles/coreclr.dir/all] Error 2
make: *** [all] Error 2
Failed to build coreclr components.

By searching around on the web a bit, I was able to discover that this is frequently the result of not having enough RAM in the box. The VM I was using had 512 MB by default, so I bumped it to 1 GB and retried. This time, the build completed successfully.

It would be useful to have a note in the build instructions indicating the required amount of RAM; it would also be cool if the error message could be tweaked to be more informative.

[jkotas]

I have added note about the minimum RAM required to the wiki. Thanks.