From: Thor Lancelot Simon <tls@rek.tjls.com>
> -mcpu=pentiumpro -march=pentium seems to be safe, though; as is
> -mcpu=pentiumpro -march=pentiumpro in a kernel build *so long as gcc
> itself was not built that way*.

% cc -v
Using builtin specs.
gcc version 2.95.3 20010315 (release)
% cat x.c
#include <sys/types.h>
#include <machine/intr.h>

static int unsafedata;

test()
{
	int s = splbio();
	unsafedata++;
	splx(s);
}
% cc -S -O2 -march=pentiumpro x.c
% cat x.s
<snip>
        movl cpl,%eax
        movl %eax,%edx
        orl imask+24,%edx
        movl %edx,cpl
        movl %eax,cpl	/* no meaning of spl, sigh */
        movl ipending,%edx
        movl %esp,%ebp
        subl $8,%esp
        incl unsafedata
        notl %eax
        testl %edx,%eax
        je .L9
        call Xspllower
.L9:


in this case, we can make unsafedata volatile to
avoid problems. but i don't think we should do so.

---
YAMAMOTO Takashi<yamt@mwd.biglobe.ne.jp>