Re: finding unused globals in the kernel

[Arnd Bergmann <arnd@arndb.de>]

On Monday 01 March 2004 15:32, Marcelo Tosatti wrote:
> 
> On Sat, 28 Feb 2004, Arnd Bergmann wrote:
> > bash /home/arnd/linux-2.6-ipc/scripts/checkunused.sh i386 arch/i386/kernel/head.o arch/i386/kernel/init_task.o   init/built-in.o  usr/built-in.o  arch/i386/kernel/built-in.o  arch/i386/mm/built-in.o  arch/i386/mach-default/built-in.o  kernel/built-in.o  mm/built-in.o  fs/built-in.o  ipc/built-in.o  security/built-in.o  crypto/built-in.o  lib/lib.a  arch/i386/lib/lib.a  lib/built-in.o  arch/i386/lib/built-in.o  drivers/built-in.o  sound/built-in.o  arch/i386/pci/built-in.o  arch/i386/oprofile/built-in.o  arch/i386/power/built-in.o  net/built-in.o
> > unreferenced definition VSYSCALL_BASE
> 
> It seems your script is behaving wrongly for the VSYSCALL_BASE case 
> (probably others too):
> 
> elf.h:
> 
> #define VSYSCALL_BASE   (__fix_to_virt(FIX_VSYSCALL))
> #define VSYSCALL_EHDR   ((const struct elfhdr *) VSYSCALL_BASE)
> #define VSYSCALL_ENTRY  ((unsigned long) &__kernel_vsyscall)
> extern void __kernel_vsyscall;

Actually, VSYSCALL_BASE is defined as an absolute symbol in
arch/i386/kernel/vsyscall.lds, so it's not as broken as one might think.
The bug is that the script cannot find symbols defined by the linker
and used only as a constant in the same linker script. Fortunately, this
isn't done in many places.

	Arnd <><