2014-07-01 9:29 GMT+02:00 Alle Meije Wink <a.m.wink@gmail.com>:

gcc.link.dll build\boost\bin.v2\libs\context\build\gcc-mingw-4.8.1\release\threading-multi\libboost_context-mgw48-mt-1_56.dll.a

    "g++"   "-Wl,--out-implib,build\boost\bin.v2\libs\context\build\gcc-mingw-4.8.1\release\threading-multi\libboost_context-mgw48-mt-1_56.dll.a" -o "build\boost\bin.v2\libs\context\build\gcc-mingw-4.8.1\release\threading-multi\libboost_context-mgw48-mt-1_56.dll"  -shared -Wl,--start-group "build\boost\bin.v2\libs\context\build\gcc-mingw-4.8.1\release\address-model-32\architecture-x86\threading-multi\asm\make_i386_ms_pe_masm.o" "build\boost\bin.v2\libs\context\build\gcc-mingw-4.8.1\release\address-model-32\architecture-x86\threading-multi\asm\jump_i386_ms_pe_masm.o" "build\boost\bin.v2\libs\co
ntext\build\gcc-mingw-4.8.1\release\threading-multi\dummy.o"  -Wl,-Bstatic  -Wl,-Bdynamic  -Wl,--end-group -mthreads

build\boost\bin.v2\libs\context\build\gcc-mingw-4.8.1\release\address-model-32\architecture-x86\threading-multi\asm\make_i386_ms_pe_masm.o: file not recognized: File format not recognized

strange - the make_i386_ms_pe_masm.o is in MS PE binary format but mingw (g++) does not recognize it.
The regression tests at http://www.boost.org/development/tests/master/developer/coroutine.html pass with mingw-4.8.2.
Do you use the code from branch master?
Maybe it is an issue of mingw-4.8.1?