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Date: Tue, 8 Oct 2013 18:51:55 -0300
From: Marcelo Tosatti <mtosatti@redhat.com>
Message-ID: <20131008215155.GA16625@amt.cnet>
References: <20131008004126.773017235@amt.cnet>
	<20131008004224.509422315@amt.cnet> <5253BC64.2060105@redhat.com>
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Subject: Re: [Qemu-devel] [patch 1/2] qemu: mempath: prefault pages manually
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-devel@nongnu.org

On Tue, Oct 08, 2013 at 10:03:48AM +0200, Paolo Bonzini wrote:
> Il 08/10/2013 02:41, Marcelo Tosatti ha scritto:
> > +        /* unblock SIGBUS */
> > +        pthread_sigmask(SIG_BLOCK, NULL, &oldset);
> > +        sigemptyset(&set);
> > +        sigaddset(&set, SIGBUS);
> > +        pthread_sigmask(SIG_UNBLOCK, &set, NULL);
> 
> Please instead modify qemu-thread-posix.c to unblock all per-thread
> signals (SIGBUS, SIGSEGV, SIGILL, SIGFPE and SIGSYS).  There is no need
> to keep those blocked.
> 
> Paolo

main-loop.c handles SIGBUS via signalfd to emulate MCEs (associated
commits). Therefore it must be blocked.

Note that what this patch does it to maintain the signal handling state
(it saves the previous state, modifies state, restores previous state) so 
that its unchanged.