Mingw builds

[Алексей Павлов]

Hi!
When I building 32-bit mingw-w64 multilib runtime without
-march\-mtune its very well, but if I use -march=i686 -mtune=core2 I
have error:
"CPU you selected does not support x86-64 instruction set"
And I have some questions:
1. If I don't specify any -march/-mtune what is used by default in GCC
when I build multilib toolchain?
2. Can I build multilib toolchain with -march=i686 or it's impossible?
3. If I use toolchain builded without -march/-mtune it generate
incorrect code with -march=corei7-avx. Is it GCC FEATURE or BUG?