Re: [PATCH] kexec jump: fix code size checking

Huang Ying
2008-08-13T03:05:31Z

On Wed, 2008-08-13 at 12:47 +1000, Simon Horman wrote:
> On Wed, Aug 13, 2008 at 09:04:35AM +0800, Huang Ying wrote:
> > Fix building issue when CONFIG_KEXEC=n. Thanks to Vivek Goyal for his
> > reminding.
> >
> > Signed-off-by: Huang Ying <ying.huang@intel.com>
> >
> > ---
> > include/asm-x86/kexec.h | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > --- a/include/asm-x86/kexec.h
> > +++ b/include/asm-x86/kexec.h
> > @@ -43,6 +43,9 @@
> >
> > #ifdef CONFIG_X86_32
> > # define KEXEC_CONTROL_CODE_MAX_SIZE 2048
> > +# ifndef CONFIG_KEXEC
> > +# define kexec_control_code_size 0
> > +# endif
> > #endif
> >
> > #ifndef __ASSEMBLY__
>
> Is it impossible to skip the linker check in the !CONFIG_KEXEC case?

It is possible. I think there are several ways to do that.

1) use #ifdef in vmlinux_32.lds.S, such as:

#ifdef CONFIG_KEXEC
ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE,
"kexec control code size is too big")
#endif

2) #define a macro for kexec check ld script in asm/kexec.h, such as:

#define LD_CHECK_KEXEC() ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE, \
"kexec control code size is too big")

and use that in vmlinux_32.lds.S.

3) #define kexec_control_code_size 0. So that the check can be passed
always. And, code size = 0 is reasonable for no code (CONFIG_KEXEC=n).

I think 3) is better. What do you think about?

Best Regards,
Huang Ying