On Mon, Feb 27, 2012 at 04:26:31PM -0800, Andrew Morton wrote:
> On Tue, 28 Feb 2012 09:19:28 +0900
> Simon Horman <[email protected]> wrote:
>
> > > > --- a/kernel/kexec.c
> > > > +++ b/kernel/kexec.c
> > > > @@ -1462,7 +1462,9 @@ static int __init crash_save_vmcoreinfo_init(void)
> > > >
> > > > VMCOREINFO_SYMBOL(init_uts_ns);
> > > > VMCOREINFO_SYMBOL(node_online_map);
> > > > +#ifdef CONFIG_MMU
> > > > VMCOREINFO_SYMBOL(swapper_pg_dir);
> > > > +#endif
> > > > VMCOREINFO_SYMBOL(_stext);
> > > > VMCOREINFO_SYMBOL(vmlist);
> > >
> > > Well, what might be the effects of this patch? nommu crashfiles will
> > > no longer have the swapper_pg_dir string? What are the chances that
> > > someone's (badly written!) downstream tool will crash and burn if this
> > > is absent?
> >
> > My understanding is that up until this patch creating a dump
> > for nonmmu platform wouldn't work.
>
> Surprised. From reading the code I expect it would have emitted
>
> SYMBOL(swapper_pg_dir)=0
Hi Andrew,
My understanding from discussion with Will earlier in this thread is that if
CONFIG_MMU is not defined then swapper_pg_dir is NULL and the current code
doesn't compile.
<quote>
The only case where it's interesting is when you have CONFIG_MMU
enabled - otherwise it's always NULL. If it's #defined as NULL, the
current code will fail at build time so simply omitting it from the
dump seems like the best bet to me (the alternative being to add a
NULL entry explicitly, but I don't see what the gains us).
</quote>
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