lkml.org 
[lkml]   [2006]   [Nov]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [patch 2.6.19-rc6] Stop gcc 4.1.0 optimizing wait_hpet_tick away
From
Date
On Wed, 2006-11-29 at 13:22 +1100, Keith Owens wrote:
> Compiling 2.6.19-rc6 with gcc version 4.1.0 (SUSE Linux),
> wait_hpet_tick is optimized away to a never ending loop and the kernel
> hangs on boot in timer setup.
>
> 0000001a <wait_hpet_tick>:
> 1a: 55 push %ebp
> 1b: 89 e5 mov %esp,%ebp
> 1d: eb fe jmp 1d <wait_hpet_tick+0x3>
>
> This is not a problem with gcc 3.3.5. Adding barrier() calls to
> wait_hpet_tick does not help, making the variables volatile does.
>
> Signed-off-by: Keith Owens <kaos@ocs.com.au>
>
> ---
> arch/i386/kernel/time_hpet.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> Index: linux-2.6/arch/i386/kernel/time_hpet.c
> ===================================================================
> --- linux-2.6.orig/arch/i386/kernel/time_hpet.c
> +++ linux-2.6/arch/i386/kernel/time_hpet.c
> @@ -51,7 +51,7 @@ static void hpet_writel(unsigned long d,
> */
> static void __devinit wait_hpet_tick(void)
> {
> - unsigned int start_cmp_val, end_cmp_val;
> + unsigned volatile int start_cmp_val, end_cmp_val;
>
> start_cmp_val = hpet_readl(HPET_T0_CMP);
> do {

When you examine the inlined functions involved, this looks an awful lot
like http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22278

Perhaps SUSE should fix their gcc instead of working around compiler
problems in the kernel?

--
Nicholas Miell <nmiell@comcast.net>

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-11-29 04:11    [W:0.092 / U:0.024 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site