From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39065) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gCrNR-0007Dw-Jc for qemu-devel@nongnu.org; Wed, 17 Oct 2018 15:21:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gCrNQ-0006es-OY for qemu-devel@nongnu.org; Wed, 17 Oct 2018 15:21:05 -0400 From: Aaron Lindsay Date: Wed, 17 Oct 2018 19:20:53 +0000 Message-ID: <20181017192013.GA25905@quinoa.localdomain> References: <20181010203735.27918-1-aclindsa@gmail.com> <20181010203735.27918-13-aclindsa@gmail.com> <0fdcad4a-c8b5-3309-d2ce-f9be901ec52a@linaro.org> In-Reply-To: <0fdcad4a-c8b5-3309-d2ce-f9be901ec52a@linaro.org> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Subject: Re: [Qemu-devel] [PATCH v6 12/14] target/arm: PMU: Set PMCR.N to 4 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Richard Henderson Cc: Aaron Lindsay , "qemu-arm@nongnu.org" , Peter Maydell , Alistair Francis , Wei Huang , Peter Crosthwaite , Michael Spradling , "qemu-devel@nongnu.org" , Digant Desai On Oct 16 17:09, Richard Henderson wrote: > On 10/10/18 1:37 PM, Aaron Lindsay wrote: > > This both advertises that we support four counters and enables them > > because the pmu_num_counters() reads this value from PMCR. > >=20 > > Signed-off-by: Aaron Lindsay > > --- > > target/arm/helper.c | 8 ++++---- > > 1 file changed, 4 insertions(+), 4 deletions(-) >=20 > It looks like this should have been folded into patch 10, > or patch 10 split to include the code changes that go with > these comment changes. By setting PMCR.N to 4, this commit is what causes all the previous implementation of non-PMCCNTR counters to become usable by the guest - both because the OS can now detect their presence in PMCR, and because the system registers used to setup/access the counters are gated on pmu_num_counters(), which uses PMCR.N to determine if a counter is implemented. That said, I'm not against merging the two patches if you feel that is cleaner. -Aaron