On Fri, 2013-06-14 at 02:44 +0000, Bjarni Ingi Gislason wrote:
> On Thu, Jun 13, 2013 at 09:10:27PM +0000, Bjarni Ingi Gislason wrote:
> > On Thu, Jun 13, 2013 at 03:07:26AM +0100, Ben Hutchings wrote:
> > > Control: tag -1 moreinfo
> > >
> > > On Wed, 2013-06-12 at 23:46 +0000, Bjarni Ingi Gislason wrote:
> > > > Package: linux-source-3.2
> > > > Version: 3.2.46-1
> > > > Severity: important
> > > >
> > > > Dear Maintainer,
> > > >
> > > > * What led up to the situation?
> > > >
> > > > Compiling error:
> > > >
> > > > In file included from include/linux/mm_types.h:15:0,
> > > > from include/linux/sched.h:64,
> > > > from arch/x86/kernel/asm-offsets.c:9:
> > > > include/linux/rcupdate.h: In function '__kfree_rcu':
> > > > include/linux/rcupdate.h:834:2: error: size of unnamed array is negative
> > > > make[1]: *** [arch/x86/kernel/asm-offsets.s] Error 1
> > > > make: *** [prepare0] Error 2
> > > >
> > > > Line 834 is BUILD_BUG_ON... in
> > > >
> > > > static __always_inline
> > > > void __kfree_rcu(struct rcu_head *head, unsigned long offset)
> > > > {
> > > > typedef void (*rcu_callback)(struct rcu_head *);
> > > >
> > > > BUILD_BUG_ON(!__builtin_constant_p(offset));
> > > >
> > > >
> > > > "offset" is declared as an "unsigned long" so can't be negative!
> > >
> > > This is a build-time assertion that the caller is passing a compile-time
> > > constant for offset. If the assertion fails it triggers this weird
> > > 'size of unnamed array is negative' error.
> > >
> > > But nothing in asm-offsets.c will be calling it, so this doesn't make
> > > sense to me.
> > >
> > > You forgot to attach your .config.
> > >
> >
> > In the main Makefile I changed "-O2" to "-O0":
> >
>
> This bug is most probably caused by the "-O0" option for "gcc" as I
> got an error when compiling an older version
>
> In file included from linux-2.6.38.5/arch/x86/include/asm/alternative.h:105:0,
> from linux-2.6.38.5/arch/x86/include/asm/bitops.h:16,
> from include/linux/bitops.h:22,
> from include/linux/kernel.h:17,
> from include/linux/sched.h:55,
> from include/linux/stackprotector.h:5,
> from arch/x86/kernel/process_32.c:12:
> linux-2.6.38.5/arch/x86/include/asm/cpufeature.h: In function
> 'prepare_to_copy':
> linux-2.6.38.5/arch/x86/include/asm/cpufeature.h:321:4: warning: asm operand
> 0 probably doesn't match constraints [enabled by default]
> linux-2.6.38.5/arch/x86/include/asm/cpufeature.h:321:4: warning: asm operand
> 0 probably doesn't match constraints [enabled by default]
> linux-2.6.38.5/arch/x86/include/asm/cpufeature.h:321:4: error: impossible
> constraint in 'asm'
> linux-2.6.38.5/arch/x86/include/asm/cpufeature.h:321:4: error: impossible
> constraint in 'asm'
> linux-2.6.38.5/arch/x86/include/asm/cpufeature.h: In function '__switch_to':
> linux-2.6.38.5/arch/x86/include/asm/cpufeature.h:321:4: warning: asm operand
> 0 probably doesn't match constraints [enabled by default]
> linux-2.6.38.5/arch/x86/include/asm/cpufeature.h:321:4: warning: asm operand
> 0 probably doesn't match constraints [enabled by default]
> make[2]: *** [arch/x86/kernel/process_32.o] Error 1
> make[1]: *** [arch/x86/kernel] Error 2
> make: *** [arch/x86] Error 2
>
> The bug is thus either in the compiler "gcc" or assember "as".It's not a bug. The kernel code relies on the compiler doing certain optimisations, which is why the Makefile always enables them. > I will compile 3.2.46-1 later with the "-O2" (default) option. Ben. -- Ben Hutchings If the facts do not conform to your theory, they must be disposed of.
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