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

    * 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


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