diff --git a/automation/build/README.md b/automation/build/README.md
index 1c040533fd..12a2b4af18 100644
--- a/automation/build/README.md
+++ b/automation/build/README.md
@@ -81,7 +81,14 @@ Building a container
 
 There is a makefile to make this process easier. You should be
 able to run `make DISTRO/VERSION` to have Docker build the container
-for you. If you define the `PUSH` environment variable when running the
+for you.
+
+Xen's dockerfiles use heredocs, which depend on the standardised dockerfile
+syntax introduced by [BuiltKit].  This should work by default starting with
+docker 23.0, or podman/buildah v1.33.  For older versions of docker, it can be
+activated with `DOCKER_BUILDKIT=1` in the environment.
+
+If you define the `PUSH` environment variable when running the
 former `make` command, it will push the container to the [registry] if
 you have access to do so and have your Docker logged into the registry.
 
@@ -101,6 +108,7 @@ env CONTAINER_NO_PULL=1 \
 make -C automation/build suse/opensuse-tumbleweed PUSH=1
 ```
 
+[BuildKit]: https://docs.docker.com/build/buildkit/
 [registry]: https://gitlab.com/xen-project/xen/container_registry
 [registry help]: https://gitlab.com/help/user/project/container_registry
 
diff --git a/automation/build/alpine/3.18-arm64v8.dockerfile b/automation/build/alpine/3.18-arm64v8.dockerfile
index 91e9022024..19fe46f841 100644
--- a/automation/build/alpine/3.18-arm64v8.dockerfile
+++ b/automation/build/alpine/3.18-arm64v8.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/arm64/v8 alpine:3.18
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/alpine/3.18.dockerfile b/automation/build/alpine/3.18.dockerfile
index 8d5dac05b0..263e9e90d8 100644
--- a/automation/build/alpine/3.18.dockerfile
+++ b/automation/build/alpine/3.18.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/amd64 alpine:3.18
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/archlinux/current-riscv64.dockerfile b/automation/build/archlinux/current-riscv64.dockerfile
index af75b5c720..f7770bf82a 100644
--- a/automation/build/archlinux/current-riscv64.dockerfile
+++ b/automation/build/archlinux/current-riscv64.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/amd64 archlinux
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/archlinux/current.dockerfile b/automation/build/archlinux/current.dockerfile
index d29f1358c2..8929e9b5f0 100644
--- a/automation/build/archlinux/current.dockerfile
+++ b/automation/build/archlinux/current.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/amd64 archlinux:base-devel
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/centos/7.dockerfile b/automation/build/centos/7.dockerfile
index 1cdc16fc05..657550f308 100644
--- a/automation/build/centos/7.dockerfile
+++ b/automation/build/centos/7.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/amd64 centos:7
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/debian/bookworm-arm64v8-arm32-gcc.dockerfile b/automation/build/debian/bookworm-arm64v8-arm32-gcc.dockerfile
index a05ffeac04..95b3f04283 100644
--- a/automation/build/debian/bookworm-arm64v8-arm32-gcc.dockerfile
+++ b/automation/build/debian/bookworm-arm64v8-arm32-gcc.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/arm64/v8 debian:bookworm
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/debian/bookworm-arm64v8.dockerfile b/automation/build/debian/bookworm-arm64v8.dockerfile
index 2c432aacb7..3ab426a082 100644
--- a/automation/build/debian/bookworm-arm64v8.dockerfile
+++ b/automation/build/debian/bookworm-arm64v8.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/arm64/v8 debian:bookworm
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/debian/bookworm-cppcheck.dockerfile b/automation/build/debian/bookworm-cppcheck.dockerfile
index 633268376d..fe4cd4a1aa 100644
--- a/automation/build/debian/bookworm-cppcheck.dockerfile
+++ b/automation/build/debian/bookworm-cppcheck.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/arm64/v8 debian:bookworm AS builder
 
 ENV DEBIAN_FRONTEND=noninteractive
diff --git a/automation/build/debian/bookworm-i386.dockerfile b/automation/build/debian/bookworm-i386.dockerfile
index 89a6503385..9a54bd7293 100644
--- a/automation/build/debian/bookworm-i386.dockerfile
+++ b/automation/build/debian/bookworm-i386.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/i386 debian:bookworm
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/debian/bookworm.dockerfile b/automation/build/debian/bookworm.dockerfile
index d893218fc4..bef44dd753 100644
--- a/automation/build/debian/bookworm.dockerfile
+++ b/automation/build/debian/bookworm.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/amd64 debian:bookworm
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/debian/bullseye-ppc64le.dockerfile b/automation/build/debian/bullseye-ppc64le.dockerfile
index 6fdfb6bc2b..e166d205f3 100644
--- a/automation/build/debian/bullseye-ppc64le.dockerfile
+++ b/automation/build/debian/bullseye-ppc64le.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/amd64 debian:bullseye-slim
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/debian/buster-gcc-ibt.dockerfile b/automation/build/debian/buster-gcc-ibt.dockerfile
index 6a3e50ef6b..ed9367aafb 100644
--- a/automation/build/debian/buster-gcc-ibt.dockerfile
+++ b/automation/build/debian/buster-gcc-ibt.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/amd64 debian:buster-slim AS builder
 
 ENV DEBIAN_FRONTEND=noninteractive
diff --git a/automation/build/debian/jessie-i386.dockerfile b/automation/build/debian/jessie-i386.dockerfile
index a8dec82bb2..f6eaa94ee5 100644
--- a/automation/build/debian/jessie-i386.dockerfile
+++ b/automation/build/debian/jessie-i386.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/i386 debian/eol:jessie
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/debian/jessie.dockerfile b/automation/build/debian/jessie.dockerfile
index 308675cac1..a870e743fc 100644
--- a/automation/build/debian/jessie.dockerfile
+++ b/automation/build/debian/jessie.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/amd64 debian/eol:jessie
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/debian/stretch-i386.dockerfile b/automation/build/debian/stretch-i386.dockerfile
index da93fed8ea..ad8db692aa 100644
--- a/automation/build/debian/stretch-i386.dockerfile
+++ b/automation/build/debian/stretch-i386.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/i386 debian:stretch
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/debian/stretch.dockerfile b/automation/build/debian/stretch.dockerfile
index 59794ed467..4dfd40b542 100644
--- a/automation/build/debian/stretch.dockerfile
+++ b/automation/build/debian/stretch.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/amd64 debian:stretch
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/fedora/29.dockerfile b/automation/build/fedora/29.dockerfile
index f473ae13e7..08edf70838 100644
--- a/automation/build/fedora/29.dockerfile
+++ b/automation/build/fedora/29.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/amd64 fedora:29
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/suse/opensuse-leap.dockerfile b/automation/build/suse/opensuse-leap.dockerfile
index 3ef33458a0..28d3338812 100644
--- a/automation/build/suse/opensuse-leap.dockerfile
+++ b/automation/build/suse/opensuse-leap.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/amd64 opensuse/leap
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/suse/opensuse-tumbleweed.dockerfile b/automation/build/suse/opensuse-tumbleweed.dockerfile
index a793601c87..077fed2226 100644
--- a/automation/build/suse/opensuse-tumbleweed.dockerfile
+++ b/automation/build/suse/opensuse-tumbleweed.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/amd64 opensuse/tumbleweed
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/ubuntu/bionic.dockerfile b/automation/build/ubuntu/bionic.dockerfile
index 910d3c4b53..cc43fc4ade 100644
--- a/automation/build/ubuntu/bionic.dockerfile
+++ b/automation/build/ubuntu/bionic.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/amd64 ubuntu:18.04
 LABEL maintainer.name="The Xen Project " \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/ubuntu/focal.dockerfile b/automation/build/ubuntu/focal.dockerfile
index 078abd56d5..cb8bb2f6fa 100644
--- a/automation/build/ubuntu/focal.dockerfile
+++ b/automation/build/ubuntu/focal.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/amd64 ubuntu:20.04
 LABEL maintainer.name="The Xen Project " \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/ubuntu/trusty.dockerfile b/automation/build/ubuntu/trusty.dockerfile
index 8bd8c085a7..e2a1bda7c3 100644
--- a/automation/build/ubuntu/trusty.dockerfile
+++ b/automation/build/ubuntu/trusty.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/amd64 ubuntu:14.04
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/ubuntu/xenial-xilinx.dockerfile b/automation/build/ubuntu/xenial-xilinx.dockerfile
index 49f27b3229..f03d62e8bd 100644
--- a/automation/build/ubuntu/xenial-xilinx.dockerfile
+++ b/automation/build/ubuntu/xenial-xilinx.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/amd64 ubuntu:16.04
 LABEL maintainer.name="The Xen Project " \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/ubuntu/xenial.dockerfile b/automation/build/ubuntu/xenial.dockerfile
index f6296d3292..168bc70ffa 100644
--- a/automation/build/ubuntu/xenial.dockerfile
+++ b/automation/build/ubuntu/xenial.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/amd64 ubuntu:16.04
 LABEL maintainer.name="The Xen Project " \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/build/yocto/yocto.dockerfile.in b/automation/build/yocto/yocto.dockerfile.in
index b0892d4203..fbaa4e191c 100644
--- a/automation/build/yocto/yocto.dockerfile.in
+++ b/automation/build/yocto/yocto.dockerfile.in
@@ -1,3 +1,5 @@
+# syntax=docker/dockerfile:1
+
 # Docker file to create an environment to build yocto with virtualization
 #
 # Arguments that can be passed during image creation using --build-arg:
diff --git a/automation/tests-artifacts/alpine/3.18-arm64v8.dockerfile b/automation/tests-artifacts/alpine/3.18-arm64v8.dockerfile
index 0e5ae7f2b4..a4542f7039 100644
--- a/automation/tests-artifacts/alpine/3.18-arm64v8.dockerfile
+++ b/automation/tests-artifacts/alpine/3.18-arm64v8.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/arm64/v8 alpine:3.18
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/tests-artifacts/alpine/3.18.dockerfile b/automation/tests-artifacts/alpine/3.18.dockerfile
index 9cde6c9ad4..311a92889b 100644
--- a/automation/tests-artifacts/alpine/3.18.dockerfile
+++ b/automation/tests-artifacts/alpine/3.18.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/amd64 alpine:3.18
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/tests-artifacts/kernel/5.19-arm64v8.dockerfile b/automation/tests-artifacts/kernel/5.19-arm64v8.dockerfile
index b0875ca0dd..22359c9066 100644
--- a/automation/tests-artifacts/kernel/5.19-arm64v8.dockerfile
+++ b/automation/tests-artifacts/kernel/5.19-arm64v8.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/arm64/v8 debian:bookworm
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/tests-artifacts/kernel/6.1.19.dockerfile b/automation/tests-artifacts/kernel/6.1.19.dockerfile
index 021bde26c7..5cf53d290c 100644
--- a/automation/tests-artifacts/kernel/6.1.19.dockerfile
+++ b/automation/tests-artifacts/kernel/6.1.19.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/amd64 debian:bookworm
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/tests-artifacts/qemu-system-aarch64/6.0.0-arm64v8.dockerfile b/automation/tests-artifacts/qemu-system-aarch64/6.0.0-arm64v8.dockerfile
index fb7b7b506e..e9f5576be7 100644
--- a/automation/tests-artifacts/qemu-system-aarch64/6.0.0-arm64v8.dockerfile
+++ b/automation/tests-artifacts/qemu-system-aarch64/6.0.0-arm64v8.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/arm64/v8 debian:bookworm
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
diff --git a/automation/tests-artifacts/qemu-system-ppc64/8.1.0-ppc64.dockerfile b/automation/tests-artifacts/qemu-system-ppc64/8.1.0-ppc64.dockerfile
index 65857147bf..e28d686492 100644
--- a/automation/tests-artifacts/qemu-system-ppc64/8.1.0-ppc64.dockerfile
+++ b/automation/tests-artifacts/qemu-system-ppc64/8.1.0-ppc64.dockerfile
@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=linux/amd64 debian:bullseye-slim
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"