Re: 2.4.15-pre4 compile problem

Linus Torvalds
2001-11-12T20:31:59Z

In article <200111121939.fACJdX309798@danapple.com>,
Daniel I. Applebaum <kernel@danapple.com> wrote:
>
>While compiling 2.4.15-pre4:
>+++++++++++++++
>gcc -D__KERNEL__ -I/usr/src/linux/include -Wall -Wstrict-prototypes -Wno-trigraphs -O2 -fomit-frame-pointer -fno-strict-aliasing -fno-common -pipe -mpreferred-stack-boundary=2 -march=i686 -c -o setup.o setup.c
>setup.c: In function `c_start':
>setup.c:2791: subscripted value is neither array nor pointer

Ugh. That's because a buggy #define on UP in x86.

It should be trivially fixed by changing include/asm-i386/processor.h:

#define cpu_data &boot_cpu_data

to

#define cpu_data (&boot_cpu_data)

in order to get the right parsing order for all users of cpu_data. Ie
just add the parenthesis around the thing.

Oh, well. "Always put parentesis around define-expands" is a really
really good rule. Along with "Always put parenthesis around the
argument expansion too".

Oh, and cleaning up the particular offending user will hide the problem
too, if you just use

cpu_data+*pos

instead of using

&cpu_data[*pos]

in arch/i386/kernel/setup.c: c_start(). Which is cleaner and simpler
anyway, and which is defined by C to be exactly the same thing (as long
as "cpu_data" behaves like a real array, not a broken #define that
depends on operator precedence around it).

I'll do both in my tree. Thanks,

Linus