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[2400:8500:1301:747:a133:130:115:230f]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7127ae06bb7sm8242227b3a.58.2024.08.20.06.50.12 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 20 Aug 2024 06:50:15 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3776.700.51\)) Subject: Re: It is correct to introduce new sys calls to stable versions? From: Miao Wang In-Reply-To: <2024082057-coherence-lethargy-3513@gregkh> Date: Tue, 20 Aug 2024 21:49:59 +0800 Cc: Xi Ruoyao , Huacai Chen , loongarch@lists.linux.dev, Sasha Levin , stable@vger.kernel.org, WANG Xuerui , linux-api@vger.kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: References: <2024082057-coherence-lethargy-3513@gregkh> To: Greg Kroah-Hartman X-Mailer: Apple Mail (2.3776.700.51) Hi, > 2024=E5=B9=B48=E6=9C=8820=E6=97=A5 21:36=EF=BC=8CGreg Kroah-Hartman = =E5=86=99=E9=81=93=EF=BC=9A >=20 > On Tue, Aug 20, 2024 at 09:19:04PM +0800, Miao Wang wrote: >> Hi, Greg >>=20 >> I saw you have included commit 7697a0fe0154 ("LoongArch: Define >> __ARCH_WANT_NEW_STAT in unistd.h") in your stable trees, which >> actually introduced new sys calls newfstatat and fstat to Loongarch. >=20 > See the documentation in that commit for why it was done. Thanks for your explanation. I totally understand the necessity of re-introducing thees two syscalls. I just wonder whether there is any limitation on what can be included in to the stable trees. If there was no limitation, theoretically, I could also maintain a so-called stable tree by applying all the patches from torvalds' tree, except those that bumps the version number. Apparently such a "stable" tree is far from stable. >=20 >> I wonder if it is correct to add new syscalls, which actually changes >> the kernel features, in stable releases, as it might confuse = downstream >> developers because they may assume the existence of a certain feature >> after a certain version. >=20 > Version numbers should never be used to be checked for anything as = they > are only a "moment in time" stamp. They do not reflect features or > capabilities or anything else. I agree with you and Cyril on the version numbers, recalling that = kernels on RHEL numbered on 3.10 contains various new features. > Test for functionality if you want to check for something, that's the > only way it will ever work on all of the variants of different > "enterprise" kernels. Thanks again for your quick reply. >=20 > thanks, >=20 > greg k-h