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Tsirkin" To: Akihiko Odaki Cc: Jason Wang , qemu-devel@nongnu.org, Yuri Benditovich , Andrew Melnychenko Subject: Re: [PATCH v3 01/11] tap: Remove tap_probe_vnet_hdr_len() Message-ID: <20231013110140-mutt-send-email-mst@kernel.org> References: <20231011153944.39572-1-akihiko.odaki@daynix.com> <20231011153944.39572-2-akihiko.odaki@daynix.com> <74139826-7e06-48c0-bb1c-0b5bf708c808@daynix.com> <12412f11-4395-460f-9523-930ad9270188@daynix.com> <20231013101508-mutt-send-email-mst@kernel.org> <29fef0dd-86b6-4cd6-bbbc-812b832d8fcf@daynix.com> <20231013103151-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Received-SPF: pass client-ip=170.10.129.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Fri, Oct 13, 2023 at 11:34:54PM +0900, Akihiko Odaki wrote: > On 2023/10/13 23:32, Michael S. Tsirkin wrote: > > On Fri, Oct 13, 2023 at 11:22:10PM +0900, Akihiko Odaki wrote: > > > On 2023/10/13 23:17, Michael S. Tsirkin wrote: > > > > On Fri, Oct 13, 2023 at 02:26:03PM +0900, Akihiko Odaki wrote: > > > > > On 2023/10/13 14:00, Jason Wang wrote: > > > > > > On Fri, Oct 13, 2023 at 12:14 PM Akihiko Odaki wrote: > > > > > > > > > > > > > > On 2023/10/13 10:38, Jason Wang wrote: > > > > > > > > On Wed, Oct 11, 2023 at 11:40 PM Akihiko Odaki wrote: > > > > > > > > > > > > > > > > > > It was necessary since an Linux older than 2.6.35 may implement the > > > > > > > > > virtio-net header but may not allow to change its length. Remove it > > > > > > > > > since such an old Linux is no longer supported. > > > > > > > > > > > > > > > > Where can I see this agreement? > > > > > > > > > > > > > > docs/about/build-platforms.rst says: > > > > > > > > The project aims to support the most recent major version at all times > > > > > > > > for up to five years after its initial release. Support for the > > > > > > > > previous major version will be dropped 2 years after the new major > > > > > > > > version is released or when the vendor itself drops support, whichever > > > > > > > > comes first. In this context, third-party efforts to extend the > > > > > > > > lifetime of a distro are not considered, even when they are endorsed > > > > > > > > by the vendor (eg. Debian LTS); the same is true of repositories that > > > > > > > > contain packages backported from later releases (e.g. Debian > > > > > > > > backports). Within each major release, only the most recent minor > > > > > > > > release is considered. > > > > > > > > > > > > > > > > For the purposes of identifying supported software versions available > > > > > > > > on Linux, the project will look at CentOS, Debian, Fedora, openSUSE, > > > > > > > > RHEL, SLES and Ubuntu LTS. Other distros will be assumed to ship > > > > > > > > similar software versions. > > > > > > > > > > > > Well it also says: > > > > > > > > > > > > """ > > > > > > If a platform is not listed here, it does not imply that QEMU won't > > > > > > work. If an unlisted platform has comparable software versions to a > > > > > > listed platform, there is every expectation that it will work. > > > > > > """ > > > > > > > > > > > > A lot of downstream have customized build scripts. > > > > > > > > > > Still Linux versions older than 2.6.35 do not look like "comparable software > > > > > versions to a listed platform" in my opinion. > > > > > > > > > > > > This is fine - I would be ok to replace support with an error message > > > > and failure. Not checking that a capability is supported however > > > > isn't a good idea. And once we do - do we still gain anything by > > > > not working around that? > > > > > > tap does still check if setting the header length succeeds so it should be > > > fine. > > > > It asserts though doesn't it? Hardly user friendly ... > > It prints an error message so the user should be able to figure out what's > missing: > fprintf(stderr, "TUNSETVNETHDRSZ ioctl() failed: %s. Exiting.\n", > strerror(errno)); OK. Acked-by: Michael S. Tsirkin