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[68.160.135.240]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6b51ef5ef88sm10292786d6.122.2024.06.21.09.59.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 21 Jun 2024 09:59:22 -0700 (PDT) Message-ID: <157b32d5-7e68-a77f-6f72-356433e4a942@redhat.com> Date: Fri, 21 Jun 2024 12:59:21 -0400 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Content-Language: en-US From: Joe Lawrence To: Sumanth Korikkar Cc: linux-s390@vger.kernel.org, hca@linux.ibm.com, jpoimboe@kernel.org, gor@linux.ibm.com, iii@linux.ibm.com, agordeev@linux.ibm.com References: <20240219132734.22881-1-sumanthk@linux.ibm.com> <4610b08d-46a4-b6fc-2ec5-a88abba7022c@redhat.com> Subject: Re: [PATCH v2 0/4] s390: compile relocatable kernel with/without fPIE In-Reply-To: <4610b08d-46a4-b6fc-2ec5-a88abba7022c@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/19/24 14:23, Joe Lawrence wrote: > On 6/19/24 13:01, Sumanth Korikkar wrote: >> Other Note: >> The latest kernel is built with -fPIC and linked with -no-pie (reference >> commit: ca888b17da9b ("s390: Compile kernel with -fPIC and link with >> -no-pie")) which also avoids generation of dynamic symbols and helps >> kpatch usecases (when num of sections >=64k sections). Also the build >> options would be similar (-fPIC in kernel and -fPIC in kpatch-build) >> >> For latest kernel, there is no need to add explicit -fPIC again >> in kpatch tool. >> >> But for the intermediate commits, yes, makes sense to add >> it in kpatch-build tools and will create one PR. >> > > Interesting! With 00cda11d3b2e ("s390: Compile kernel with -fPIC and > link with -no-pie") it sounds like the original vmlinux would be built > with -fPIC as well, so the optimization decisions re: __mmput() would > likely be the same. I can retry the tests with v6.10-rcX to verify. > To follow up, all of the kpatch-build integration tests work with v6.10.0-rc4 :) as the kernel is built with -fPIC and so are the kpatch reference and patched builds. For pre-v6.10 kernels, I think there may be some instances where a patch author may need to account for slight build differences to appease kpatch-build expectations as I noticed here. -- Joe