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([2001:b07:6468:f312:47e0:e742:75ba:b84d]) by smtp.gmail.com with ESMTPSA id p9sm4265440wmg.34.2020.10.03.00.50.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 03 Oct 2020 00:50:32 -0700 (PDT) Subject: Re: [PATCH] meson.build: Don't look for libudev for static builds To: luoyonggang@gmail.com, Peter Maydell References: <20201002105239.2444-1-peter.maydell@linaro.org> From: Paolo Bonzini Message-ID: Date: Sat, 3 Oct 2020 09:50:31 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=63.128.21.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/03 02:43:20 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -23 X-Spam_score: -2.4 X-Spam_bar: -- X-Spam_report: (-2.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.256, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: QEMU Developers Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 03/10/20 09:24, 罗勇刚(Yonggang Luo) wrote: > > > On Fri, Oct 2, 2020 at 9:11 PM Peter Maydell > wrote: >> >> On Fri, 2 Oct 2020 at 14:05, Paolo Bonzini > wrote: >> > >> > On 02/10/20 14:35, Peter Maydell wrote: >> > > >> > > It would be better to do the "see if a static library is present" >> > > test. This isn't too hard to do in configure (compare that >> > > six line fix to the detection of libgio). Hopefully it is >> > > not too hard to do in meson ? >> > >> > Yes, something like: >> > >> > if enable_static >> >   skeleton = 'int main(void) { return 0; }' >> >   if not cc.links(skeleton, dependencies: libudev) >> >     if get_option('mpath').enabled() >> >         error('Cannot link with libudev') >> >       else >> >         warning('Cannot link with libudev, disabling') >> >         libudev = not_found >> >       endif >> >     endif >> >   endif >> > endif >> >> This duplicates the information that the thing that depends >> on libudev is mpath. Can we put this in a wrapper around >> dependency() so that we could just say something like >>   libudev = compile_checked_dependency('libudev', >>                        required: get_option('mpath').enabled(), >>                        static: enable_static) >> > Hi Bonzini, > This looks like a frequently used function, can we upstrem to meson? Yes, I think adding a "links" argument to dependency (similar to find_library's has_headers argument) makes sense. That would be written dependency('libudev', required: get_option('mpath').enabled(), static: enable_static, links: skeleton) But anyway that shouldn't be a blocker for more improvements to qemu's meson.build. Now that we have 5-10 dependencies converted we have a clearer idea of how to abstract the tests. Paolo