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    SubjectRe: [PATCH] tracing: Fix TRACING_SUPPORT dependency

    * Steven Rostedt <rostedt@goodmis.org> wrote:

    >
    > On Sat, 21 Mar 2009, Ingo Molnar wrote:
    >
    > >
    > > * Anton Vorontsov <avorontsov@ru.mvista.com> wrote:
    > >
    > > > On Fri, Mar 20, 2009 at 08:57:43PM +0100, Ingo Molnar wrote:
    > > > >
    > > > > * Anton Vorontsov <avorontsov@ru.mvista.com> wrote:
    > > > >
    > > > > > On Fri, Mar 20, 2009 at 08:04:28PM +0100, Ingo Molnar wrote:
    > > > > > >
    > > > > > > * Anton Vorontsov <avorontsov@ru.mvista.com> wrote:
    > > > > > >
    > > > > > > > commit 40ada30f9621fbd831ac2437b9a2a399aad34b00 ("tracing: clean
    > > > > > > > up menu"), despite the "clean up" in its purpose, introduced
    > > > > > > > behavioural change for Kconfig symbols: we no longer able to
    > > > > > > > select tracing support on PPC32 (because IRQFLAGS_SUPPORT isn't
    > > > > > > > yet implemented).
    > > > > > >
    > > > > > > Could you please solve this by implementing proper
    > > > > > > irqflag-tracing support? It's been available upstream for almost
    > > > > > > three years. It's needed for lockdep support as well, etc.
    > > > > >
    > > > > > Breaking things via clean up patches is an interesting method of
    > > > > > encouraging something to implement. ;-)
    > > > > >
    > > > > > Surely I'll look into implementing irqflags tracing, but
    > > > > > considering that no one ever needed this for almost three years,
    > > > > > [...]
    > > > >
    > > > > Weird, there's no lockdep support?
    > > >
    > > > *ashamed*: apparently no such support currently exist for PPC32. ;-)
    > >
    > > Hm, do all the tracers even compile on ppc32 with your patch?
    > >
    > > We had periodic build failures on weird, unmaintained architectures
    > > that had no irqflags-tracing support and hence didnt know the
    > > raw_irqs_save/restore primitives ...
    > >
    > > I'm not trying to make things more difficult for you (and we can
    > > apply your patch if it builds fine and does not cause problems
    > > elsewhere), but there were some real downsides to not having proper
    > > irq APIs ...
    >
    > Note, the issue is not with the hooks into local_irq_save/restore,
    > but with the entry.S code. That code is very sensitive where the
    > irqs are enabled and disabled.

    i know. What i'm talking about is that non-lockdep architectures
    have the habit of not defining raw_local_irq_save() - which the
    tracing core relies on.

    Ingo


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