Messages in this thread | | | Subject | Re: [PATCH 09/30] x86_64: ifdef out struct thread_struct::ip | From | Jaswinder Singh Rajput <> | Date | Fri, 10 Apr 2009 16:22:08 +0530 |
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On Fri, 2009-04-10 at 11:20 +0200, Ingo Molnar wrote: > * Jaswinder Singh Rajput <jaswinder@kernel.org> wrote: > > > On Thu, 2009-04-09 at 20:53 -0700, Matt Helsley wrote: > > > On Fri, Apr 10, 2009 at 06:35:22AM +0400, Alexey Dobriyan wrote: > > > > struct thread_struct::ip isn't used on x86_64, struct pt_regs::ip is used > > > > instead. > > > > > > > > kgdb should be reading 0, but I can't check it. > > > > > > > > Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> > > > > --- > > > > > > > > arch/x86/include/asm/processor.h | 2 ++ > > > > arch/x86/kernel/kgdb.c | 2 +- > > > > 2 files changed, 3 insertions(+), 1 deletion(-) > > > > > > > > --- a/arch/x86/include/asm/processor.h > > > > +++ b/arch/x86/include/asm/processor.h > > > > @@ -421,7 +421,9 @@ struct thread_struct { > > > > unsigned short fsindex; > > > > unsigned short gsindex; > > > > #endif > > > > +#ifdef CONFIG_X86_32 > > > > unsigned long ip; > > > > +#endif > > > > #ifdef CONFIG_X86_64 > > > > unsigned long fs; > > > > #endif > > > > > > Do these make struct thread_struct behave better in cachelines (smaller, > > > less aliasing)? Can we really fit more in the slab du jour? > > > > > > Otherwise it seems like we're littering these structs with #ifdefs > > > and not really saving anything. If these #ifdefs don't save any space why not > > > just put in a comment: > > > > > > > unsigned long ip; /* Used only on i386 */ > > > > > > Or maybe even: > > > > > > union { > > > unsigned long ip; /* Used only on i386 */ > > > unsigned long fs; /* Used only on x86_64 */ > > > }; > > > > > > > Can we do it like this: > > unsigned long ip_fs; /* ip: i386, fs: x86_64 */ > > > > I am using same variable for both cases, or we can use some better > > name than ip_fs. I am assuming either it is i386 or x86_64 machine > > ;-) > > This is the least clean variant amongst all the suggestions. >
Yes, this was a wakeful call for you.
I send dozen of emails in last 24 hours to you for your feedback.
I do not need reply for this email. Please send reply for other emails.
Thanks,
-- JSR
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