From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id 20973A0350; Wed, 1 Jul 2020 17:36:15 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 905571D446; Wed, 1 Jul 2020 17:36:14 +0200 (CEST) Received: from wout5-smtp.messagingengine.com (wout5-smtp.messagingengine.com [64.147.123.21]) by dpdk.org (Postfix) with ESMTP id 192081C2F5 for ; Wed, 1 Jul 2020 17:36:12 +0200 (CEST) Received: from compute7.internal (compute7.nyi.internal [10.202.2.47]) by mailout.west.internal (Postfix) with ESMTP id A8F409EC; Wed, 1 Jul 2020 11:36:10 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute7.internal (MEProxy); Wed, 01 Jul 2020 11:36:11 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=monjalon.net; h= from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding:content-type; s=fm1; bh= iRA7eu/XbPNGNh9RwK2dK4yJ7zRJNq81yOUSwIZ272s=; b=CI6SA9osGL7wicyp jkhLmM8zH/NMBJ+alqI+Hu583UwP5ud32W9f/aAXR1TErI9rXm8H4TPXYPlXPZbg 5V6rgge+MA4bEjHPtYNgvgmLb/10sexjhi0EF4DjJZKpAUdGIXXaBPqPFdfmJ0gv btUpVab4TB0+sn9NVybt9NdeV5YKFHVyhaCUuKczfROsolAUb+bsvL4P9S3xPamG XAG87jeZzDgxFh7S3ld64DLaNF2W2M2fa7g58e+a56S/VC5w+NW4sCQSsvQk/S4w 1pbVqwgAbGsBAGaDQvTMaFSu4mSMb0LnyrMV1M+jLYmP7CJ2ZxHFObFNx2Noa2+6 ad7Msg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:in-reply-to:message-id:mime-version:references :subject:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm3; bh=iRA7eu/XbPNGNh9RwK2dK4yJ7zRJNq81yOUSwIZ27 2s=; b=Gx14yMj95YKfkVvXjUhHlsvtBGIohh/A8wrR8yFC6IJTjakfHYhx1nxwH 6Y+SEWZ9LKQguKuUyFhZRb5y/nHYRkNKLnz1Ag5HcW7pcb6eXp5PsWhFDVJv6KPT Hn7/wR9Fbe53OlQjWsr+EfO+bGjpICcJnHo/Q9tTctB56cfpSYtUo5Zx+kMxXd8D mq59Qb1GcuNSSE0JmMPKIqWf5nM7PR5OG6kzUHEOPz3cW9KDjv+0GVPBWrCaqVIt +FWVGzyzt6bfH0/dNi8BSdeEsf6PovzTfSrWvrvXMZ9sQZ/mpHRkvMzW07VGdrRo SEPl+g1+mgug2cVDc+Jm7cGTlbNdg== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduiedrtddvgdelfecutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenuc fjughrpefhvffufffkjghfggfgtgesthfuredttddtvdenucfhrhhomhepvfhhohhmrghs ucfoohhnjhgrlhhonhcuoehthhhomhgrshesmhhonhhjrghlohhnrdhnvghtqeenucggtf frrghtthgvrhhnpedugefgvdefudfftdefgeelgffhueekgfffhfeujedtteeutdejueei iedvffegheenucfkphepjeejrddufeegrddvtdefrddukeegnecuvehluhhsthgvrhfuih iivgeptdenucfrrghrrghmpehmrghilhhfrhhomhepthhhohhmrghssehmohhnjhgrlhho nhdrnhgvth X-ME-Proxy: Received: from xps.localnet (184.203.134.77.rev.sfr.net [77.134.203.184]) by mail.messagingengine.com (Postfix) with ESMTPA id 66077328006A; Wed, 1 Jul 2020 11:36:08 -0400 (EDT) From: Thomas Monjalon To: Bruce Richardson Cc: dev@dpdk.org, david.marchand@redhat.com, ktraynor@redhat.com, bluca@debian.org, sunil.pai.g@intel.com Date: Wed, 01 Jul 2020 17:36:07 +0200 Message-ID: <5534902.P14CUFCJsY@thomas> In-Reply-To: <20200701151651.GG595@bricha3-MOBL.ger.corp.intel.com> References: <20200429100831.398-1-bruce.richardson@intel.com> <7587667.Wdl7rU7Jnr@thomas> <20200701151651.GG595@bricha3-MOBL.ger.corp.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Subject: Re: [dpdk-dev] [PATCH v3 5/7] build/pkg-config: output driver libs first for static build X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" 01/07/2020 17:16, Bruce Richardson: > On Wed, Jul 01, 2020 at 04:42:33PM +0200, Thomas Monjalon wrote: > > 30/06/2020 16:14, Bruce Richardson: > > > When calling pkg-config --static --libs, pkg-config will always output the > > > regular libs first, and then the extra libs from libraries.private field, > > > > s/libraries.private/Libs.private/ > > > > > since the assumption is that those are additional dependencies for building > > > statically that the .a files depend upon. > > > > > > However, for DPDK, we only link the driver files for static builds, and > > > those need to come *before* the regular libraries. To get this result, we > > > need two pkgconfig files for DPDK, one for the shared libs, and a second > > > for the static libs and drivers, which depends upon the first. Using a > > > dependency means that the shared libs are printed only after the > > > libraries.private field rather than before. > > > > s/libraries.private/Libs.private/ > > > > > Without this patch, the linking works in DPDK because in all cases we > > > specify the libraries after the drivers in the Libs.private line, ensuring > > > that the references to the libs from the drivers can be resolved. The > > > current output is therefore of the form, "(shared)libs, drivers, > > > (static)libs", while after this patch the output is, "drivers, > > > (static)libs, (shared)libs". The former case will not work if we use the > > > --whole-archive flag on the static libs as it will lead to duplicate > > > definitions due to some references having been previously resolved from the > > > shared libraries. By ensuring the shared libraries come last in the link > > > link, this issue does not occur, as duplicate references when linking the > > > shared libs will be ignored. > > > > > > Signed-off-by: Bruce Richardson > > > Acked-by: Luca Boccassi > > > Acked-by: Sunil Pai G > > > --- > > > +# When calling pkg-config --static --libs, pkg-config will always output the > > > +# regular libs first, and then the extra libs from libraries.private field, > > > +# since the assumption is that those are additional dependencies for building > > > +# statically that the .a files depend upon. However, for DPDK, we only link > > > +# the driver files for static builds, and those need to come *before* the > > > +# regular libraries. To get this result, we need two pkgconfig files for DPDK, > > > +# one for the shared libs, and a second for the static libs and drivers, which > > > +# depends upon the first. Using a dependency means that the shared libs are > > > +# printed only after the libraries.private field rather than before. > > > > This is not obvious. In order to avoid messing it up in future, > > I suggest this longer reword: > > > > # When calling pkg-config --static --libs, pkg-config will always output the > > # regular libs first, and then the extra libs from Libs.private field, > > # since the assumption is that those are additional dependencies for building > > # statically that the .a files depend upon. The output order of .pc fields is: > > # Cflags Libs Libs.private Requires Requires.private > > # The fields Requires* are for package names. > > # The flags of the DPDK libraries must be defined in Libs* fields. > > # However, the DPDK drivers are linked only in static builds (Libs.private), > > # and those need to come *before* the regular libraries (Libs field). > > # This requirement is satisfied by moving the regular libs in a separate file > > # included in the field Requires (after Libs.private). > > # Another requirement is to allow linking dependencies as shared libraries, > > # while linking static DPDK libraries and drivers. It is satisfied by > > # listing the static files in Libs.private with the explicit syntax -l:libfoo.a. > > # As a consequence, the regular DPDK libraries are already listed as static > > # in the field Libs.private. The second occurences of DPDK libraries, > > # included from Requires and used for shared library linkage case, > > # are skipped in the case of static linkage thanks to the flag --as-needed. > > > > # Link order summary: > > # libdpdk.Libs.private: whole-archive(static drivers/libs), drivers deps flags > > # libdpdk.Requires: libdpdk-libs package > > # libdpdk-libs.Libs: as-needed(shared libs) > > # libdpdk-libs.Libs.private: libs deps flags > > # libdpdk.pc.Requires.private: deps packages > > > > > > If you agree, I could change this comment while merging. > > I would add my Signed-off ;) > > > > This seems generally ok, but probably should just be added as part of patch > #7 when all parts of the above have been applied. > > Couple of comments: > * One small nit is that cflags are not output as part of the --libs call, so > you can remove them from the list on line 5 of the comment. They aren't > really relevant to this comment/essay. Yes, I will remove Cflags. > * I find the link-order summary to actually be more confusing than helpful. > I think the text block is explanatory enough. It just confuses things > introducing the extra details of what goes in the requires-private or > libs-private of the libdpdk.pc file. That's just regular stuff, unrelated > to the changes or to DPDK special-case of needing private libs first. The intent of this summary was to help navigating for future changes in this area. Personnaly it helps me, but it is maybe more a developer note that can be deduced from the rest. I can remove it.