Re: [Patch 5/8] ia64: implement crashkernel=auto

Ingo Molnar
2009-08-22T11:18:50Z

* Andrew Morton <akpm@linux-foundation.org> wrote:

> On Fri, 21 Aug 2009 02:55:04 -0400
> Amerigo Wang <amwang@redhat.com> wrote:
>
> > +#ifdef CONFIG_KEXEC_AUTO_RESERVE
> > +#define ARCH_HAS_DEFAULT_CRASH_SIZE
> > +static inline
> > +unsigned long long arch_default_crash_size(unsigned long long total_size)
> > +{
> > + if (total_size >= 4ULL<<30 && total_size < 12ULL<<30)
> > + return 1ULL<<28;
> > + else if (total_size >= 12ULL<<30 && total_size < 128ULL<<30)
> > + return 1ULL<<29;
> > + else if (total_size >= 128ULL<<30 && total_size < 256ULL<<30)
> > + return 3ULL<<28;
> > + else if (total_size >= 256ULL<<30 && total_size < 378ULL<<30)
> > + return 1ULL<<30;
> > + else if (total_size >= 318ULL<<30 && total_size < 512ULL<<30)
> > + return 3ULL<<29;
> > + else if (total_size >= 512ULL<<30 && total_size < 768ULL<<30)
> > + return 2ULL<<30;
> > + else if (total_size >= 768ULL<<30)
> > + return 3ULL<<30;
> > +}
> > +#include <asm-generic/kexec.h>
> > +#endif
>
> a) Why on earth is this inlined?
>
> b) Please consider making arch_default_crash_size() a __weak
> function. You'll probably find the result to be pleasing.
>
> c) If we can't use __weak then please don't add
> ARCH_HAS_DEFAULT_CRASH_SIZE. Instead do this trick:
>
>
> #ifndef arch_default_crash_size
> static inline unsigned long long arch_default_crash_size(unsigned long long total_size)
> {
> ...
> }
> #define arch_default_crash_size arch_default_crash_size
> #endif
>
> because i) it's good to standardise on something and ii) one less
> symbol gets added to the kernel.
>
> d) why is asm-generic/kexec.h only included in asm/kexec.h if
> CONFIG_KEXEC_AUTO_RESERVE happened to be defined? That makes no
> sense - there may be a multitude of reasons why asm/kexec.h wants
> to include asm-generic/kexec.h.

e) All the 'else' statements are superflous and make it all harder
to read.

f) 2ULL<<30 should be written as 1ULL<31, to keep things consistent.

g) A nice comment explaining the purpose and logic wouldnt hurt.

Ingo