From mboxrd@z Thu Jan 1 00:00:00 1970 From: Luca Boccassi Subject: Re: [EXT] [PATCH] config: change default cache line size for ARMv8 with meson Date: Wed, 09 Jan 2019 13:14:29 +0000 Message-ID: <1547039669.6022.57.camel@debian.org> References: <20190109093915.40882-1-yskoh@mellanox.com> <68eb1e77e09e396a229920f10487b6e95ddce5c8.camel@marvell.com> <1547029195.6022.54.camel@debian.org> <9c0a7ac4623c45d19e216f670ea7cd064f12b1ae.camel@marvell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Cc: "shahafs@mellanox.com" , "Gavin.Hu@arm.com" , "dev@dpdk.org" To: Jerin Jacob Kollanukkaran , "thomas@monjalon.net" , "yskoh@mellanox.com" Return-path: Received: from mail-wm1-f65.google.com (mail-wm1-f65.google.com [209.85.128.65]) by dpdk.org (Postfix) with ESMTP id 2AE231B47B for ; Wed, 9 Jan 2019 14:14:32 +0100 (CET) Received: by mail-wm1-f65.google.com with SMTP id p6so8159976wmc.1 for ; Wed, 09 Jan 2019 05:14:32 -0800 (PST) In-Reply-To: <9c0a7ac4623c45d19e216f670ea7cd064f12b1ae.camel@marvell.com> List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On Wed, 2019-01-09 at 10:52 +0000, Jerin Jacob Kollanukkaran wrote: > On Wed, 2019-01-09 at 10:19 +0000, Luca Boccassi wrote: > > On Wed, 2019-01-09 at 10:09 +0000, Jerin Jacob Kollanukkaran wrote: > > > On Wed, 2019-01-09 at 01:39 -0800, Yongseok Koh wrote: > > > > --------------------------------------------------------------- > > > > ---- > > > > --- > > > > In config/arm64_armv8_linuxapp_gcc, maximum available cache > > > > line > > > > size > > > > (128B) in arm64 implementations is set by default for generic > > > > config. > > > > However, setting 64B is preferable for meson build in order to > > > > support > > > > majority of CPUs which don't have Implementor ID or Part Number > > > > programmed > > > > on chip. > > >=20 > > > Adding Luca to get input from distro build perspective. > > >=20 > > > If I understand it correctly, distro build will be using > > > the generic config/arm/arm64_armv8_linuxapp_gcc for generic > > > build. > > > If so, We can not change cache line size for generic config > > > as mentined the reason are > > > https://mails.dpdk.org/archives/dev/2019-January/122441.html > > >=20 > > >=20 > > > I think, I way forward is to add > > > config/arm/arm64_a72_linuxapp_gcc > > > for meson. This config can be used for all SoC with A72 armv8=C2=A0 > > > implementation and may have sym link to specfific SoC to avoid > > > confusion to end users. > >=20 > > For Meson, I recently sent a patch to use a common and stable > > baseline > > machine arg if the uses sets it to "default": > >=20 > > https://patches.dpdk.org/patch/49477/ > >=20 > > For distros, I think if, within that path, the cache size is set to > > the > > minimum common denominator like the -march is, it will be fine. > >=20 > > At that point, what happens for "native" or otherwise specified > > builds > > it will not affect distros (as long as they use "default" like > > Debian > > and Ubuntu do). > >=20 >=20 > Thanks for the input >=20 > > Does this answer your question? >=20 >=20 > Kind of.. Will you be building "the generic image" on ANY arm64 > machine > with following command? >=20 > meson configure -Dmachine=3Ddefault > meson build > cd build > ninja > ninja install >=20 > If so, This patch will change the cache line size of generic build. > Right? Yes, that's the command used everywhere on Debian/Ubuntu, regardless of the machine type, and this patch will change the value for those cases as far as I can see. Please bear in mind that I know really little about arm, so I am not sure which should be the default for maximum compatibility. --=20 Kind regards, Luca Boccassi