Andi Kleen wrote:
> "H. Peter Anvin" <hpa@zytor.com> writes:
> 
>>I don't know what would cause the stack to be misaligned, however.
> 
> x86-64 kernel doesn't guarantee the stack to be 16 byte aligned
> (although it usually is). If you need 16 byte alignment you have 
> to align yourself.
> 

OK, that's unfortunate... per our discussion I really think this is a 
bug, since the compiler still does 16-byte alignment, and thus we're 
taking the cost without the benefit.

I'll send in the attached patch for now, but at some point I'd like to 
fix this.  Unfortunately I still don't have an x86-64 machine that I can 
actually compile and install kernels on; I only have access to an x86-64 
userspace, so I'm a bit limited in what I can test.

Michael: Perhaps you could apply this patch and test it out for me?

	-hpa