On Thu, Nov 19, 2009 at 4:49 PM, Richard Guenther <richard.guent...@gmail.com> wrote: > 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.
Just checking it seems you must be using -mincoming-stack-boundary=2 instead but keep the preferred stack boundary at 4. Richard.
