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Subject: Re: [PATCH v4 10/10] powerpc/watchpoint: Remove 512 byte boundary
To:     Jordan Niethe <jniethe5@gmail.com>
Cc:     Michael Ellerman <mpe@ellerman.id.au>, mikey@neuling.org,
        apopple@linux.ibm.com, Paul Mackerras <paulus@samba.org>,
        Nicholas Piggin <npiggin@gmail.com>,
        Christophe Leroy <christophe.leroy@c-s.fr>,
        naveen.n.rao@linux.vnet.ibm.com, peterz@infradead.org,
        jolsa@kernel.org, oleg@redhat.com, fweisbec@gmail.com,
        mingo@kernel.org, pedromfc@br.ibm.com, miltonm@us.ibm.com,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
        Ravi Bangoria <ravi.bangoria@linux.ibm.com>
References: <20200717040958.70561-1-ravi.bangoria@linux.ibm.com>
 <20200717040958.70561-11-ravi.bangoria@linux.ibm.com>
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From:   Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Message-ID: <8ee4424b-ca42-082d-d845-0e06357c8b8f@linux.ibm.com>
Date:   Tue, 21 Jul 2020 08:54:54 +0530
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Hi Jordan,

On 7/20/20 12:24 PM, Jordan Niethe wrote:
> On Fri, Jul 17, 2020 at 2:11 PM Ravi Bangoria
> <ravi.bangoria@linux.ibm.com> wrote:
>>
>> Power10 has removed 512 bytes boundary from match criteria. i.e. The watch
>> range can cross 512 bytes boundary.
> It looks like this change is not mentioned in ISA v3.1 Book III 9.4
> Data Address Watchpoint. It could be useful to mention that in the
> commit message.

Yes, ISA 3.1 Book III 9.4 has a documentation mistake and hopefully it
will be fixed in the next version of ISA. Though, this is mentioned in
ISA 3.1 change log:

   Multiple DEAW:
   Added a second Data Address Watchpoint. [H]DAR is
   set to the first byte of overlap. 512B boundary is
   removed.

I'll mention this in the commit description.

> Also I wonder if could add a test for this to the ptrace-hwbreak selftest?

Yes, I already have a selftest for this in perf-hwbreak. Will send that soon.

Thanks,
Ravi