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Tue, 21 Apr 2026 06:47:15 -0700 (PDT) Date: Tue, 21 Apr 2026 06:47:11 -0700 From: Stephen Hemminger To: Jakub Kicinski Cc: davem@davemloft.net, netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, andrew+netdev@lunn.ch, horms@kernel.org, corbet@lwn.net, skhan@linuxfoundation.org, marcel@holtmann.org, luiz.dentz@gmail.com, mchehab+huawei@kernel.org, jani.nikula@intel.com, gregkh@linuxfoundation.org, demarchi@kernel.org, rdunlap@infradead.org, justonli@chromium.org, ivecera@redhat.com, jonathan.cameron@huawei.com, kees@kernel.org, marco.crivellari@suse.com, ferr.lambarginio@gmail.com, nihaal@cse.iitm.ac.in, mingo@kernel.org, tglx@kernel.org, linmq006@gmail.com, linux-doc@vger.kernel.org, linux-bluetooth@vger.kernel.org Subject: Re: [PATCH net-deletions] net: remove ISDN subsystem and Bluetooth CMTP Message-ID: <20260421064711.04e3e71a@phoenix.local> In-Reply-To: <20260421022108.1299678-1-kuba@kernel.org> References: <20260421022108.1299678-1-kuba@kernel.org> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 20 Apr 2026 19:21:07 -0700 Jakub Kicinski wrote: > Remove the ISDN (mISDN, CAPI) subsystem and Bluetooth CMTP protocol > from the kernel tree. > > ISDN is a pretty old technology and it's unclear whether anyone still > uses it. I went over the last few years of git history and all the > commits are either tree-wide conversions or syzbot/static analyzer > fixes. > > When we discussed removal in the past IIRC there were some concerns > about ISDN still being used in parts of Germany. Unfortunately, the > code base is quite old, none of the current maintainers are familiar > with it and AI tools will have a field day finding bugs here. > > Delete this code and preserve it in an out-of-tree repository > for any remaining users: > https://github.com/linux-netdev/mod-orphan > > UAPI constants AF_ISDN/PF_ISDN and the SELinux isdn_socket class > are preserved for ABI stability, but the rest of uAPI is removed. > > Signed-off-by: Jakub Kicinski > --- Acked-by: Stephen Hemminger Will remove it from iproute2-next as well