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    SubjectRe: [RFC GIT PULL] hw-breakpoints: Rewrite on top of perf counters
    On Thu, Sep 10, 2009 at 08:09:56PM +1000, Paul Mackerras wrote:
    > Frederic Weisbecker writes:
    >
    > > This is a rewrite of the hardware breakpoints on top of perf counters.
    >
    > On powerpc, it doesn't build. I get:
    >
    > CC kernel/perf_counter.o
    > kernel/perf_counter.c:31:31: error: asm/hw_breakpoint.h: No such file or directory
    > kernel/perf_counter.c: In function 'bp_perf_counter_init':
    > kernel/perf_counter.c:3964: error: implicit declaration of function 'register_perf_hw_breakpoint'
    > kernel/perf_counter.c:3966: error: implicit declaration of function '__register_perf_hw_breakpoint'
    > kernel/perf_counter.c:3968: error: 'perf_ops_bp' undeclared (first use in this function)
    > kernel/perf_counter.c:3968: error: (Each undeclared identifier is reported only once
    > kernel/perf_counter.c:3968: error: for each function it appears in.)
    > make[2]: *** [kernel/perf_counter.o] Error 1
    > make[1]: *** [kernel] Error 2
    > make: *** [sub-make] Error 2
    >
    > Seems like every architecture now needs an asm/hw_breakpoint.h. What
    > is the minimum required in that file? Looks like we would require a
    > perf_ops_bp, at least.
    >
    > Could you please either arrange things so that architectures that
    > don't have hardware breakpoints hooked up to perf_counters don't need
    > an asm/hw_breakpoint.h, or add minimal versions of that file for every
    > architecture, so as not to break bisection unnecessarily?
    >
    > Paul.


    I focused so much on the breakpoint <- perf dependency that I've even
    forgotten the opposite dependency :)

    I'll fix it in the 3rd patch.
    We have an <asm-generic/hw-breakpoint.h> so I can just add an
    #ifdef HAVE_HW_BREAKPOINT on its top.

    Also I'll export the various breakpoints api dependant out of
    kernel/perf_counter.c and provide stubs for the off-case.

    Thanks.



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