From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id CC1FB45D44; Tue, 19 Nov 2024 17:23:39 +0100 (CET) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id B8D1840B94; Tue, 19 Nov 2024 17:23:39 +0100 (CET) Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by mails.dpdk.org (Postfix) with ESMTP id DB0324028A; Tue, 19 Nov 2024 17:23:38 +0100 (CET) Received: by linux.microsoft.com (Postfix, from userid 1213) id 3403C206BCEE; Tue, 19 Nov 2024 08:23:38 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 3403C206BCEE DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1732033418; bh=sIiDYwh1QywaJm1s2cFlmSXIJF5GiVvXOGabRWH4GGk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MqVaRYhBRwJhjEtGMdxj439tYBM0yww+cXx83KNcr/S9ISVv6eUXS+OGwXDNQjq6v CmSPA9Xz8nj6VenpiHjgoUP8s477Rkt/u6+WkexMC3/CjHZOKW3i6kym7eslMl5Whr 9neGGIDasRrve+msrwgn58tIHgppMiDeOirqKbbY= Date: Tue, 19 Nov 2024 08:23:38 -0800 From: Andre Muezerie To: Konstantin Ananyev Cc: Morten =?iso-8859-1?Q?Br=F8rup?= , "roretzla@linux.microsoft.com" , "techboard@dpdk.org" , "Yuying.Zhang@intel.com" , "aman.deep.singh@intel.com" , "anatoly.burakov@intel.com" , "bruce.richardson@intel.com" , "byron.marohn@intel.com" , "conor.walsh@intel.com" , "cristian.dumitrescu@intel.com" , "david.hunt@intel.com" , "dev@dpdk.org" , "dsosnowski@nvidia.com" , "gakhil@marvell.com" , "jerinj@marvell.com" , "jingjing.wu@intel.com" , "kirill.rybalchenko@intel.com" , "konstantin.v.ananyev@yandex.ru" , "matan@nvidia.com" , "orika@nvidia.com" , "radu.nicolau@intel.com" , "ruifeng.wang@arm.com" , "sameh.gobriel@intel.com" , "sivaprasad.tummala@amd.com" , "skori@marvell.com" , "stephen@networkplumber.org" , "suanmingm@nvidia.com" , "vattunuru@marvell.com" , "viacheslavo@nvidia.com" , "vladimir.medvedkin@intel.com" , "yipeng1.wang@intel.com" Subject: Re: [PATCH v5 01/16] eal: provide pack start macro for MSVC Message-ID: <20241119162338.GA1105@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net> References: <1710968771-16435-1-git-send-email-roretzla@linux.microsoft.com> <1731990941-10001-1-git-send-email-andremue@linux.microsoft.com> <1731990941-10001-2-git-send-email-andremue@linux.microsoft.com> <98CBD80474FA8B44BF855DF32C47DC35E9F8D2@smartserver.smartshare.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org On Tue, Nov 19, 2024 at 11:00:56AM +0000, Konstantin Ananyev wrote: > > > > -----Original Message----- > > From: Morten Brørup > > Sent: Tuesday, November 19, 2024 8:32 AM > > To: Andre Muezerie ; roretzla@linux.microsoft.com; techboard@dpdk.org > > Cc: Yuying.Zhang@intel.com; aman.deep.singh@intel.com; anatoly.burakov@intel.com; bruce.richardson@intel.com; > > byron.marohn@intel.com; conor.walsh@intel.com; cristian.dumitrescu@intel.com; david.hunt@intel.com; dev@dpdk.org; > > dsosnowski@nvidia.com; gakhil@marvell.com; jerinj@marvell.com; jingjing.wu@intel.com; kirill.rybalchenko@intel.com; > > konstantin.v.ananyev@yandex.ru; matan@nvidia.com; orika@nvidia.com; radu.nicolau@intel.com; ruifeng.wang@arm.com; > > sameh.gobriel@intel.com; sivaprasad.tummala@amd.com; skori@marvell.com; stephen@networkplumber.org; > > suanmingm@nvidia.com; vattunuru@marvell.com; viacheslavo@nvidia.com; vladimir.medvedkin@intel.com; > > yipeng1.wang@intel.com > > Subject: RE: [PATCH v5 01/16] eal: provide pack start macro for MSVC > > > > > From: Andre Muezerie [mailto:andremue@linux.microsoft.com] > > > Sent: Tuesday, 19 November 2024 05.35 > > > > > > From: Tyler Retzlaff > > > > > > MSVC struct packing is not compatible with GCC. Provide a macro that > > > can be used to push existing pack value and sets packing to 1-byte. > > > The existing __rte_packed macro is then used to restore the pack value > > > prior to the push. > > > > > > Instead of providing macros exclusively for MSVC and for GCC the > > > existing macro is deliberately utilized to trigger a warning if no > > > existing packing has been pushed allowing easy identification of > > > locations where the __rte_msvc_pack is missing. > > > > > > Signed-off-by: Tyler Retzlaff > > > --- > > > lib/eal/include/rte_common.h | 4 +++- > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > diff --git a/lib/eal/include/rte_common.h > > > b/lib/eal/include/rte_common.h > > > index 4d299f2b36..409890863e 100644 > > > --- a/lib/eal/include/rte_common.h > > > +++ b/lib/eal/include/rte_common.h > > > @@ -103,8 +103,10 @@ typedef uint16_t unaligned_uint16_t; > > > * Force a structure to be packed > > > */ > > > #ifdef RTE_TOOLCHAIN_MSVC > > > -#define __rte_packed > > > +#define __rte_msvc_pack __pragma(pack(push, 1)) > > > +#define __rte_packed __pragma(pack(pop)) > > > #else > > > +#define __rte_msvc_pack > > > #define __rte_packed __attribute__((__packed__)) > > > #endif > > > > > > -- > > > 2.47.0.vfs.0.3 > > > > Before proceeding with this, can we please discuss the alternative, proposed here: > > https://inbox.dpdk.org/dev/CAJFAV8yStgiBbe+Nkt9mC30r0+ZP64_kGuRHOzqd90RD2HXZyw@mail.gmail.com/ > > > > The definition of the packing macro in OVS, for reference: > > https://github.com/openvswitch/ovs/blob/main/include/openvswitch/compiler.h#L209 > > Yes, that one looks much nicer to me too. > Could I also ask to avoid creeping _msvc_ into DPDK namespace. > These are all good comments. I'll look more into it. > > > > The current solution requires __rte_packed to be placed at the end of a structure, although __attribute__((packed)) is normally > > allowed at the beginning (between the "struct" tag and the name of the structure), which introduces a high risk of contributors placing > > it "incorrectly", thus causing errors. > > > > I have a strong preference for an __RTE_PACKED(decl) variant. > > > > Here's a third alternative: > > #ifdef RTE_TOOLCHAIN_MSVC > > #define __rte_msvc_pack_begin __pragma(pack(push, 1)) > > #define __rte_msvc_pack_end __pragma(pack(pop)) > > #else > > #define __rte_msvc_pack_begin > > #define __rte_msvc_pack_end > > #endif > > > > The third alternative is also problematic, e.g. if a contributor forgets the _end after the structure declaration, or adds another > > structure declaration before the _end. > > > > -Morten