I think Andrew Ip has similar problem with his EPIA. I think Bochs BIOS and VGA BIOS are running with cache on. Try changing mem.basek value from 768 to 1024 in northbridge.c, it will report 0xC0000-0xFFFFF area as no ram, so it will not cached.
I have got it fix when enabling VIDEO_CONSOLE, IIRC. As Ron said, you probably don't need ADLO when you don't need video console.
-Andrew