From: David Gibson <dwg@au1.ibm.com>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Michael Neuling <mikey@neuling.org>,
Benjamin Herrenschmidt <benh@au1.ibm.com>,
shaggy@linux.vnet.ibm.com,
Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>,
Will Deacon <will.deacon@arm.com>,
linuxppc-dev@ozlabs.org, Alan Stern <stern@rowland.harvard.edu>,
paulus@samba.org, "K.Prasad" <prasad@linux.vnet.ibm.com>,
Roland McGrath <roland@redhat.com>
Subject: Re: [Patch 1/1] PPC64-HWBKPT: Implement hw-breakpoints for PPC64
Date: Tue, 9 Mar 2010 10:57:45 +1100 [thread overview]
Message-ID: <20100308235745.GE4993@yookeroo> (raw)
In-Reply-To: <20100226015807.GF5592@nowhere>
On Fri, Feb 26, 2010 at 02:58:12AM +0100, Frederic Weisbecker wrote:
> On Mon, Feb 22, 2010 at 06:47:46PM +0530, K.Prasad wrote:
[snip]
> > > Oh, why does ptrace use a one-shot behaviour in ppc? Breakpoints
> > > only trigger once?
> > >
> >
> > Yes, ptrace breakpoints on PPC64 are designed to trigger once and this
> > patch retains that behaviour. It is very convenient to use one-shot
> > behaviour on archs where exceptions are triggered-before-execute.
>
> Ah, Why?
Because otherwise you have jump through some tricky hoops so that when
gdb (or whatever) resumes after the breakpoint, you don't immediately
retrap in the same place. I gather x86 has hardware assistance to do
this, but powerpc doesn't.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
next prev parent reply other threads:[~2010-03-09 0:46 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-15 5:56 [Patch 0/1] PPC64-HWBKPT: Hardware Breakpoint interfaces - ver XIII K.Prasad
2010-02-15 5:59 ` [Patch 1/1] PPC64-HWBKPT: Implement hw-breakpoints for PPC64 K.Prasad
2010-02-21 1:01 ` Frederic Weisbecker
2010-02-22 13:17 ` K.Prasad
2010-02-23 10:57 ` K.Prasad
2010-02-26 17:52 ` Frederic Weisbecker
2010-02-26 1:58 ` Frederic Weisbecker
2010-03-08 23:57 ` David Gibson [this message]
2010-03-09 2:14 ` K.Prasad
-- strict thread matches above, loose matches on Subject: below --
2010-03-08 18:12 [Patch 0/1] PPC64-HWBKPT: Hardware Breakpoint interfaces - ver XIV K.Prasad
2010-03-08 18:14 ` [Patch 1/1] PPC64-HWBKPT: Implement hw-breakpoints for PPC64 K.Prasad
2010-03-12 6:19 ` Benjamin Herrenschmidt
2010-03-15 6:29 ` K.Prasad
2010-04-07 8:03 ` Benjamin Herrenschmidt
2010-04-14 3:53 ` K.Prasad
2010-03-23 5:33 ` Paul Mackerras
2010-03-23 7:28 ` K.Prasad
2010-01-21 8:46 [Patch 0/1] PPC64-HWBKPT: Hardware Breakpoint interfaces - ver XII K.Prasad
2010-01-21 8:49 ` [Patch 1/1] PPC64-HWBKPT: Implement hw-breakpoints for PPC64 K.Prasad
2010-01-19 9:12 [Patch 0/1] PPC64-HWBKPT: Hardware Breakpoint interfaces - ver XI K.Prasad
2010-01-19 9:14 ` [Patch 1/1] PPC64-HWBKPT: Implement hw-breakpoints for PPC64 K.Prasad
2009-12-11 16:04 K.Prasad
2009-12-14 0:56 ` Roland McGrath
2009-12-14 18:03 ` K.Prasad
2009-12-14 19:26 ` Roland McGrath
2009-12-17 19:03 ` K.Prasad
2010-01-19 9:40 ` K.Prasad
2010-01-19 10:03 ` Roland McGrath
2010-01-22 7:14 ` K.Prasad
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