On Thu, Nov 19, 2009 at 4:45 PM, H. Peter Anvin <h...@zytor.com> wrote: > On 11/19/2009 07:37 AM, Thomas Gleixner wrote: >> >> modified function start on a handful of functions only seen with gcc >> 4.4.x on x86 32 bit: >> >> push %edi >> lea 0x8(%esp),%edi >> and $0xfffffff0,%esp >> pushl -0x4(%edi) >> push %ebp >> mov %esp,%ebp >> ... >> call mcount >> > > The real questions is why we're aligning the stack in the kernel. It is > probably not what we want -- we don't use SSE for anything but a handful > of special cases in the kernel, and we don't want the overhead.
It's likely because you have long long vars on the stack which is faster when they are aligned. -mno-stackrealign may do what you want (or may not, I have not checked). I assume you already use -mpreferred-stack-boundary=2. Richard.
