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[192.35.17.28]) by gmr-mx.google.com with ESMTPS id 64si1043483wma.1.2019.01.17.02.06.25 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 17 Jan 2019 02:06:25 -0800 (PST) Received-SPF: pass (google.com: domain of henning.schild@siemens.com designates 192.35.17.28 as permitted sender) client-ip=192.35.17.28; Authentication-Results: gmr-mx.google.com; spf=pass (google.com: domain of henning.schild@siemens.com designates 192.35.17.28 as permitted sender) smtp.mailfrom=henning.schild@siemens.com Received: from mail1.sbs.de (mail1.sbs.de [192.129.41.35]) by goliath.siemens.de (8.15.2/8.15.2) with ESMTPS id x0HA6O0g016392 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Thu, 17 Jan 2019 11:06:24 +0100 Received: from md1za8fc.ad001.siemens.net ([139.25.69.119]) by mail1.sbs.de (8.15.2/8.15.2) with ESMTP id x0HA6OGG000367; Thu, 17 Jan 2019 11:06:24 +0100 Date: Thu, 17 Jan 2019 11:06:24 +0100 From: Henning Schild To: Jan Kiszka Cc: isar-users Subject: Re: custom-kernel downgrade and linux-libc-dev Message-ID: <20190117110624.40c457c4@md1za8fc.ad001.siemens.net> In-Reply-To: References: <20190116172724.7811cfba@md1za8fc.ad001.siemens.net> X-Mailer: Claws Mail 3.15.0-dirty (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TUID: NSrA54ITD2WE Am Wed, 16 Jan 2019 20:16:14 +0100 schrieb Jan Kiszka : > On 16.01.19 17:27, Henning Schild wrote: > > Hi, > > > > our custom kernel builds always generate a linux-libc-dev package > > matching the kernel kernel version. So for a cip you would get > > linux-libc-dev-4.4.xx. > > > > Prebuild debian packages from upstream depend on a linux-libc-dev >= > > . I.e. you want build-essential in stretch, > > you will end up with a "Depends: linux-libc-dev (>= 4.9.65-3)" > > somewhere in your deps chain. > > But if you are building a custom kernel lower than the expected > > version you will end up with a smaller linux-libc-dev in the isar > > repo. And the strong pinning will leave apt no choice but to give > > up and trying to resolve the problem. So if you want to include i.e > > build-essential into an image with a kernel downgrade, you will not > > be able to build that image. > > > > That issue is especially problematic since it will creap into the > > buildchroot after the package was deployed by the first kernel > > build. And you will end up with a setup where partial rebuilds > > involving buildchroot changes will not work anymore. > > > > In the layer i discovered this problem in i now remove the > > linux-libc-dev package in a do_deploy_deb_prepend. That seems to be > > a working hack for the downgrade case, but might not be the best > > idea for an upgrade case. > > > > But my current suggestion would be to ignore the whole issue of > > kernel header compatibilty and never deploy the linux-libc-dev > > package from custom kernel builds. Thoughts? > > Better solution is to only deploy linux-libc-dev if it is newer than > the distro version. If you do not do that, you would break > applications that explicitly want to exploit interfaces of newer > kernels. True, i thought that would be hard to detect. But i think i found some shell code to easily make that comparison using debian tools. Henning > Jan >