Re: [PATCH][8/8] Arch agnostic completely out of line locks / x86_64

[Andi Kleen]

On Mon, Sep 06, 2004 at 12:19:24PM -0400, Zwane Mwaikambo wrote:
> Hi Andi,
> 
> On Mon, 6 Sep 2004, Andi Kleen wrote:
> 
> > That is with frame pointers enabled. Indeed with frame pointers
> > on it is not true you still have to special case that.
> 
> Yes that was with frame pointers enabled, but the following was compiled 
> without frame pointers, i'm still not sure it's safe to use *esp.

No, it's not unfortunately. gcc is aligning the stack 
to 8 bytes for floating point. It would if you compiled the file with 
-mpreferred-stack-boundary=4. Actually AFAIK this is only useful
for floating point anyways, so it would be a good idea to always
compile the kernel with this option.

On x86-64 it should just work.

-Andi



> 
> 00000070 <_spin_lock>:
>   70:   83 ec 04                sub    $0x4,%esp
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