install of "openvpn-dco-dkms" fails on Debian 11 with kernel "5.10.0-36"

I did a upgrade of my Debian 11 machine (`apt update` and `apt dist-upgrade`). This upgraded my Kernel from "5.10.0-35" to "5.10.0-36" (`linux-image-5.10.0-36-amd64`). Openvpn and the dco package are installed via the `build.openvpn.net/debian/openvpn/stable` repository: ```bash # dpkg -l | grep openvpn ii openvpn 2.6.15-bullseye0 amd64 virtual private network daemon ii openvpn-dco-dkms 0.2.20250922-bullseye0 all DCO (Data-Channel Offload) kernel module for OpenVPN) ``` With kernel "5.10.0-36" the dkms build fails ("5.10.0-34" and "5.10.0-35" work without an error): ```bash # apt install openvpn-dco-dkms Reading package lists... Done Building dependency tree... Done Reading state information... Done openvpn-dco-dkms is already the newest version (0.2.20250922-bullseye0). 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. 1 not fully installed or removed. After this operation, 0 B of additional disk space will be used. Do you want to continue? [Y/n] y Setting up openvpn-dco-dkms (0.2.20250922-bullseye0) ... Removing old ovpn-dco-0.2.20250922 DKMS files... -------- Uninstall Beginning -------- Module: ovpn-dco Version: 0.2.20250922 Kernel: 5.10.0-35-amd64 (x86_64) ------------------------------------- Status: Before uninstall, this module version was ACTIVE on this kernel. ovpn-dco-v2.ko: - Uninstallation - Deleting from: /lib/modules/5.10.0-35-amd64/updates/dkms/ - Original module - No original module was found for this module on this kernel. - Use the dkms install command to reinstall any previous module version. depmod... DKMS: uninstall completed. ------------------------------ Deleting module version: 0.2.20250922 completely from the DKMS tree. ------------------------------ Done. Loading new ovpn-dco-0.2.20250922 DKMS files... Building for 5.10.0-35-amd64 5.10.0-36-amd64 Building initial module for 5.10.0-35-amd64 Done. ovpn-dco-v2.ko: Running module version sanity check. - Original module - No original module exists within this kernel - Installation - Installing to /lib/modules/5.10.0-35-amd64/updates/dkms/ depmod... DKMS: install completed. Building initial module for 5.10.0-36-amd64 Error! Bad return status for module build on kernel: 5.10.0-36-amd64 (x86_64) Consult /var/lib/dkms/ovpn-dco/0.2.20250922/build/make.log for more information. dpkg: error processing package openvpn-dco-dkms (--configure): installed openvpn-dco-dkms package post-installation script subprocess returned error exit status 10 Errors were encountered while processing: openvpn-dco-dkms E: Sub-process /usr/bin/dpkg returned an error code (1) ``` ```bash # cat /var/lib/dkms/ovpn-dco/0.2.20250922/build/make.log DKMS make.log for ovpn-dco-0.2.20250922 for kernel 5.10.0-36-amd64 (x86_64) Tue Nov 4 12:05:37 CET 2025 /var/lib/dkms/ovpn-dco/0.2.20250922/build/gen-compat-autoconf.sh /var/lib/dkms/ovpn-dco/0.2.20250922/build/compat-autoconf.h make -C /lib/modules/5.10.0-36-amd64/build M=/var/lib/dkms/ovpn-dco/0.2.20250922/build PWD=/var/lib/dkms/ovpn-dco/0.2.20250922/build REVISION=0.2.20250922 CONFIG_OVPN_DCO_V2=m INSTALL_MOD_DIR=updates/ modules make[1]: Entering directory '/usr/src/linux-headers-5.10.0-36-amd64' CC [M] /var/lib/dkms/ovpn-dco/0.2.20250922/build/drivers/net/ovpn-dco/main.o CC [M] /var/lib/dkms/ovpn-dco/0.2.20250922/build/drivers/net/ovpn-dco/bind.o In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h: In function ‘ovpn_udp_tunnel6_xmit_skb’: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:42: warning: passing argument 5 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:149:46: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 149 | struct net_device *dev, struct in6_addr *saddr, | ~~~~~~~~~~~~~~~~~^~~~~ In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:49: warning: passing argument 6 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:150:22: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 150 | struct in6_addr *daddr, | ~~~~~~~~~~~~~~~~~^~~~~ In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h: In function ‘ovpn_udp_tunnel6_xmit_skb’: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:42: warning: passing argument 5 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:149:46: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 149 | struct net_device *dev, struct in6_addr *saddr, | ~~~~~~~~~~~~~~~~~^~~~~ In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:49: warning: passing argument 6 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:150:22: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 150 | struct in6_addr *daddr, | ~~~~~~~~~~~~~~~~~^~~~~ CC [M] /var/lib/dkms/ovpn-dco/0.2.20250922/build/drivers/net/ovpn-dco/crypto.o CC [M] /var/lib/dkms/ovpn-dco/0.2.20250922/build/drivers/net/ovpn-dco/ovpn.o In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h: In function ‘ovpn_udp_tunnel6_xmit_skb’: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:42: warning: passing argument 5 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:149:46: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 149 | struct net_device *dev, struct in6_addr *saddr, | ~~~~~~~~~~~~~~~~~^~~~~ In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:49: warning: passing argument 6 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:150:22: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 150 | struct in6_addr *daddr, | ~~~~~~~~~~~~~~~~~^~~~~ In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h: In function ‘ovpn_udp_tunnel6_xmit_skb’: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:42: warning: passing argument 5 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:149:46: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 149 | struct net_device *dev, struct in6_addr *saddr, | ~~~~~~~~~~~~~~~~~^~~~~ In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:49: warning: passing argument 6 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:150:22: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 150 | struct in6_addr *daddr, | ~~~~~~~~~~~~~~~~~^~~~~ CC [M] /var/lib/dkms/ovpn-dco/0.2.20250922/build/drivers/net/ovpn-dco/peer.o CC [M] /var/lib/dkms/ovpn-dco/0.2.20250922/build/drivers/net/ovpn-dco/sock.o In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h: In function ‘ovpn_udp_tunnel6_xmit_skb’: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:42: warning: passing argument 5 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:149:46: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 149 | struct net_device *dev, struct in6_addr *saddr, | ~~~~~~~~~~~~~~~~~^~~~~ In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:49: warning: passing argument 6 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:150:22: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 150 | struct in6_addr *daddr, | ~~~~~~~~~~~~~~~~~^~~~~ In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h: In function ‘ovpn_udp_tunnel6_xmit_skb’: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:42: warning: passing argument 5 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:149:46: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 149 | struct net_device *dev, struct in6_addr *saddr, | ~~~~~~~~~~~~~~~~~^~~~~ In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:49: warning: passing argument 6 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:150:22: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 150 | struct in6_addr *daddr, | ~~~~~~~~~~~~~~~~~^~~~~ CC [M] /var/lib/dkms/ovpn-dco/0.2.20250922/build/drivers/net/ovpn-dco/stats.o CC [M] /var/lib/dkms/ovpn-dco/0.2.20250922/build/drivers/net/ovpn-dco/netlink.o In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h: In function ‘ovpn_udp_tunnel6_xmit_skb’: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:42: warning: passing argument 5 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:149:46: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 149 | struct net_device *dev, struct in6_addr *saddr, | ~~~~~~~~~~~~~~~~~^~~~~ In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:49: warning: passing argument 6 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:150:22: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 150 | struct in6_addr *daddr, | ~~~~~~~~~~~~~~~~~^~~~~ In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h: In function ‘ovpn_udp_tunnel6_xmit_skb’: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:42: warning: passing argument 5 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:149:46: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 149 | struct net_device *dev, struct in6_addr *saddr, | ~~~~~~~~~~~~~~~~~^~~~~ In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:49: warning: passing argument 6 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:150:22: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 150 | struct in6_addr *daddr, | ~~~~~~~~~~~~~~~~~^~~~~ CC [M] /var/lib/dkms/ovpn-dco/0.2.20250922/build/drivers/net/ovpn-dco/crypto_aead.o CC [M] /var/lib/dkms/ovpn-dco/0.2.20250922/build/drivers/net/ovpn-dco/pktid.o In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h: In function ‘ovpn_udp_tunnel6_xmit_skb’: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:42: warning: passing argument 5 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:149:46: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 149 | struct net_device *dev, struct in6_addr *saddr, | ~~~~~~~~~~~~~~~~~^~~~~ In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:49: warning: passing argument 6 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:150:22: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 150 | struct in6_addr *daddr, | ~~~~~~~~~~~~~~~~~^~~~~ CC [M] /var/lib/dkms/ovpn-dco/0.2.20250922/build/drivers/net/ovpn-dco/tcp.o In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h: In function ‘ovpn_udp_tunnel6_xmit_skb’: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:42: warning: passing argument 5 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:149:46: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 149 | struct net_device *dev, struct in6_addr *saddr, | ~~~~~~~~~~~~~~~~~^~~~~ In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:49: warning: passing argument 6 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:150:22: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 150 | struct in6_addr *daddr, | ~~~~~~~~~~~~~~~~~^~~~~ CC [M] /var/lib/dkms/ovpn-dco/0.2.20250922/build/drivers/net/ovpn-dco/udp.o In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h: In function ‘ovpn_udp_tunnel6_xmit_skb’: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:42: warning: passing argument 5 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:149:46: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 149 | struct net_device *dev, struct in6_addr *saddr, | ~~~~~~~~~~~~~~~~~^~~~~ In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:49: warning: passing argument 6 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:150:22: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 150 | struct in6_addr *daddr, | ~~~~~~~~~~~~~~~~~^~~~~ In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/drivers/net/ovpn-dco/tcp.c: In function ‘ovpn_tcp_init’: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:158:26: error: ‘struct proto’ has no member named ‘stream_memory_read’; did you mean ‘stream_memory_free’? 158 | #define sock_is_readable stream_memory_read | ^~~~~~~~~~~~~~~~~~ /var/lib/dkms/ovpn-dco/0.2.20250922/build/drivers/net/ovpn-dco/tcp.c:483:16: note: in expansion of macro ‘sock_is_readable’ 483 | ovpn_tcp_prot.sock_is_readable = ovpn_tcp_sock_is_readable; | ^~~~~~~~~~~~~~~~ make[4]: *** [/usr/src/linux-headers-5.10.0-36-common/scripts/Makefile.build:291: /var/lib/dkms/ovpn-dco/0.2.20250922/build/drivers/net/ovpn-dco/tcp.o] Fehler 1 make[4]: *** Es wird auf noch nicht beendete Prozesse gewartet.... In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h: In function ‘ovpn_udp_tunnel6_xmit_skb’: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:42: warning: passing argument 5 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:149:46: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 149 | struct net_device *dev, struct in6_addr *saddr, | ~~~~~~~~~~~~~~~~~^~~~~ In file included from <command-line>: /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:69:49: warning: passing argument 6 of ‘udp_tunnel6_xmit_skb’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 69 | udp_tunnel6_xmit_skb(dst, sk, skb, dev, saddr, daddr, prio, ttl, label, | ^~~~~ In file included from /var/lib/dkms/ovpn-dco/0.2.20250922/build/linux-compat.h:45, from <command-line>: /usr/src/linux-headers-5.10.0-36-common/include/net/udp_tunnel.h:150:22: note: expected ‘struct in6_addr *’ but argument is of type ‘const struct in6_addr *’ 150 | struct in6_addr *daddr, | ~~~~~~~~~~~~~~~~~^~~~~ make[3]: *** [/usr/src/linux-headers-5.10.0-36-common/scripts/Makefile.build:508: /var/lib/dkms/ovpn-dco/0.2.20250922/build/drivers/net/ovpn-dco] Fehler 2 make[2]: *** [/usr/src/linux-headers-5.10.0-36-common/Makefile:1875: /var/lib/dkms/ovpn-dco/0.2.20250922/build] Fehler 2 make[1]: *** [/usr/src/linux-headers-5.10.0-36-common/Makefile:192: __sub-make] Error 2 make[1]: Leaving directory '/usr/src/linux-headers-5.10.0-36-amd64' make: *** [Makefile:51: all] Error 2 ``` Current workaround was to downgrade the kernel: ```bash apt install linux-headers-5.10.0-35-amd64 linux-headers-5.10.0-35-common linux-image-5.10.0-35-amd64 apt purge linux-headers-5.10.0-36-amd64 linux-headers-5.10.0-36-common linux-image-5.10.0-36-amd64 reboot ``` If more information or tests are needed please feel free to ask.