Hi,
Do you explicitly specify HAVE_GCC=48 somewhere, or you just tried it with the default gcc 4.5.3? If you are using the default gcc 4.5.3, your first post means that kernels compiled by gcc 4.5.3 with -O2 didn't work but works with -O2 -fno-reorder-blocks?
I just compiled a new kernel and sets with -V HAVE_GCC=48, installed and rebooted. It boots fine. I'll be compiling overnight but so far everyhing looks good!
John