>[2] I had to change all '.global' to '.globl' in arm.s and
>arm/emit.mlp.  I have no idea what that signifies.

Only that Apple's assembler only understands .globl. Gas (the assembler
in GNU binutils) should accept both .global and .globl, so it is probably
safe to use the latter only. There is no difference in semantics.

Another pseudo-op that sometimes causes problems is .align whose exact
behaviour with respect to its argument varies between platforms.
Both gas and Apple's as accept .p2align, so this is usually a safer
choice.