Default values of "struct item *items[MAX_ITEMS]" array?

[Andriy Korud]

It seems to be compiler/optimization problem - the same kernel compiled with 2.95.4 works fine, however code compiles with 3.x fails.
Maybe compiler optimization just throws away kernel bss zeroing code?

Andriy


-----Original Message-----
From:	Richard Guenther [ mailto:rguenth@tat.physik.uni-tuebingen.de ]
Sent:	Thu 13.05.2004 20:24
To:	Andriy Korud
Cc:	gcc@gcc.gnu.org
Subject:	Re: Default values of "struct item *items[MAX_ITEMS]" array?

Andriy Korud wrote:
> Hi, I'm trying to compile linux kernel (2.4.25) from ppc405 and have the following problem:
> After 
> 
> struct item *items[MAX_ITEMS];
> 
> each element of items[] is initialized to 0xffffffff and following code 
> 
> if (items[item] != NULL) {
>   items[item]->field = value;
> }
> 
> gives kernel oops (as expected - trying to reference memory at address 0xffffffff). 
> When I compile and run the same code on host PC - array is initialized with zeros and everything is fine.
> GCC versions tried - 3.2.3, 3.3.2, 3.3.3.
> 
> The questions is: I am doing something wrong or this is a bug or feature of gcc?

gcc is probably putting the array into BSS section and the kernel fails 
to zero that.  You can try using -fno-zero-initialized-in-bss, but I 
don't know if this affects uninitialized variables, too.

Richard.