diff --git a/packages/eio-ssl/eio-ssl.0.1.1/opam b/packages/eio-ssl/eio-ssl.0.1.1/opam
index d9d1ff973d8..b63364b740c 100644
--- a/packages/eio-ssl/eio-ssl.0.1.1/opam
+++ b/packages/eio-ssl/eio-ssl.0.1.1/opam
@@ -10,6 +10,7 @@ depends: [
   "ocaml" {>= "5.0"}
   "ssl" {>= "0.5.13"}
   "eio_main" {>= "0.7"}
+  "eio" {<"0.10"}
   "odoc" {with-doc}
 ]
 build: [
diff --git a/packages/eio/eio.0.10/opam b/packages/eio/eio.0.10/opam
new file mode 100644
index 00000000000..457a13471bf
--- /dev/null
+++ b/packages/eio/eio.0.10/opam
@@ -0,0 +1,57 @@
+opam-version: "2.0"
+synopsis: "Effect-based direct-style IO API for OCaml"
+description: "An effect-based IO API for multicore OCaml with fibers."
+maintainer: ["anil@recoil.org"]
+authors: ["Anil Madhavapeddy" "Thomas Leonard"]
+license: "ISC"
+homepage: "https://github.com/ocaml-multicore/eio"
+doc: "https://ocaml-multicore.github.io/eio/"
+bug-reports: "https://github.com/ocaml-multicore/eio/issues"
+depends: [
+  "dune" {>= "3.7"}
+  "ocaml" {>= "5.0.0"}
+  "bigstringaf" {>= "0.9.0"}
+  "cstruct" {>= "6.0.1"}
+  "lwt-dllist"
+  "optint" {>= "0.1.0"}
+  "psq" {>= "0.2.0"}
+  "fmt" {>= "0.8.9"}
+  "hmap" {>= "0.8.1"}
+  "domain-local-await" {>= "0.1.0"}
+  "crowbar" {>= "0.2" & with-test}
+  "mtime" {>= "2.0.0"}
+  "mdx" {>= "2.2.0" & with-test}
+  "alcotest" {>= "1.4.0" & with-test}
+  "dscheck" {>= "0.1.0" & with-test}
+  "odoc" {with-doc}
+]
+conflicts: [
+  "ocaml-base-compiler" {< "5.0.0~beta1"}
+  "ocaml-variants" {< "5.0.0~beta1"}
+  "ocaml-system" {< "5.0.0~beta1"}
+  "seq" {< "0.3"}
+]
+build: [
+  ["dune" "subst"] {dev}
+  [
+    "dune"
+    "build"
+    "-p"
+    name
+    "-j"
+    jobs
+    "@install"
+    "@runtest" {with-test}
+    "@doc" {with-doc}
+  ]
+]
+dev-repo: "git+https://github.com/ocaml-multicore/eio.git"
+url {
+  src:
+    "https://github.com/ocaml-multicore/eio/releases/download/v0.10/eio-0.10.tbz"
+  checksum: [
+    "sha256=390f7814507b8133d6c25e3a67a742d731c7ca66252b287b1fb0e3ad4d10eecc"
+    "sha512=9c0c9088b178df9799aaae9deb803a802228f1329cbe452479c90e80a13985d9c364ea86ee14e4e759133940f9f6065c7e8ece509d176fb1e347c5320f00a494"
+  ]
+}
+x-commit-hash: "687ebf99a6ab10ce5d85f4a3335d8e2e94c2b875"
diff --git a/packages/eio_linux/eio_linux.0.10/opam b/packages/eio_linux/eio_linux.0.10/opam
new file mode 100644
index 00000000000..6655c32d781
--- /dev/null
+++ b/packages/eio_linux/eio_linux.0.10/opam
@@ -0,0 +1,44 @@
+opam-version: "2.0"
+synopsis: "Eio implementation for Linux using io-uring"
+description: "An Eio implementation for Linux using io-uring."
+maintainer: ["anil@recoil.org"]
+authors: ["Anil Madhavapeddy" "Thomas Leonard"]
+license: "ISC"
+homepage: "https://github.com/ocaml-multicore/eio"
+doc: "https://ocaml-multicore.github.io/eio/"
+bug-reports: "https://github.com/ocaml-multicore/eio/issues"
+depends: [
+  "dune" {>= "3.7"}
+  "alcotest" {>= "1.4.0" & with-test}
+  "eio" {= version}
+  "mdx" {>= "2.2.0" & with-test}
+  "logs" {>= "0.7.0"}
+  "fmt" {>= "0.8.9"}
+  "cmdliner" {>= "1.1.0" & with-test}
+  "uring" {>= "0.5"}
+  "odoc" {with-doc}
+]
+build: [
+  ["dune" "subst"] {dev}
+  [
+    "dune"
+    "build"
+    "-p"
+    name
+    "-j"
+    jobs
+    "@install"
+    "@runtest" {with-test}
+    "@doc" {with-doc}
+  ]
+]
+dev-repo: "git+https://github.com/ocaml-multicore/eio.git"
+url {
+  src:
+    "https://github.com/ocaml-multicore/eio/releases/download/v0.10/eio-0.10.tbz"
+  checksum: [
+    "sha256=390f7814507b8133d6c25e3a67a742d731c7ca66252b287b1fb0e3ad4d10eecc"
+    "sha512=9c0c9088b178df9799aaae9deb803a802228f1329cbe452479c90e80a13985d9c364ea86ee14e4e759133940f9f6065c7e8ece509d176fb1e347c5320f00a494"
+  ]
+}
+x-commit-hash: "687ebf99a6ab10ce5d85f4a3335d8e2e94c2b875"
diff --git a/packages/eio_main/eio_main.0.10/opam b/packages/eio_main/eio_main.0.10/opam
new file mode 100644
index 00000000000..2236d859422
--- /dev/null
+++ b/packages/eio_main/eio_main.0.10/opam
@@ -0,0 +1,44 @@
+opam-version: "2.0"
+synopsis: "Effect-based direct-style IO mainloop for OCaml"
+description: "Selects an appropriate Eio backend for the current platform."
+maintainer: ["anil@recoil.org"]
+authors: ["Anil Madhavapeddy" "Thomas Leonard"]
+license: "ISC"
+homepage: "https://github.com/ocaml-multicore/eio"
+doc: "https://ocaml-multicore.github.io/eio/"
+bug-reports: "https://github.com/ocaml-multicore/eio/issues"
+depends: [
+  "dune" {>= "3.7"}
+  "mdx" {>= "2.2.0" & with-test}
+  "kcas" {>= "0.3.0" & with-test}
+  "yojson" {>= "2.0.2" & with-test}
+  "eio_linux" {= version & os = "linux"}
+  "eio_posix" {= version & os-family != "windows"}
+  "eio_windows" {= version & os-family = "windows"}
+  "odoc" {with-doc}
+]
+build: [
+  ["dune" "subst"] {dev}
+  [
+    "dune"
+    "build"
+    "-p"
+    name
+    "-j"
+    jobs
+    "@install"
+    "@runtest" {with-test}
+    "@doc" {with-doc}
+  ]
+]
+dev-repo: "git+https://github.com/ocaml-multicore/eio.git"
+url {
+  src:
+    "https://github.com/ocaml-multicore/eio/releases/download/v0.10/eio-0.10.tbz"
+  checksum: [
+    "sha256=390f7814507b8133d6c25e3a67a742d731c7ca66252b287b1fb0e3ad4d10eecc"
+    "sha512=9c0c9088b178df9799aaae9deb803a802228f1329cbe452479c90e80a13985d9c364ea86ee14e4e759133940f9f6065c7e8ece509d176fb1e347c5320f00a494"
+  ]
+}
+x-commit-hash: "687ebf99a6ab10ce5d85f4a3335d8e2e94c2b875"
+x-ci-accept-failures: ["macos-homebrew"]
diff --git a/packages/eio_posix/eio_posix.0.10/opam b/packages/eio_posix/eio_posix.0.10/opam
new file mode 100644
index 00000000000..9b689fa42ba
--- /dev/null
+++ b/packages/eio_posix/eio_posix.0.10/opam
@@ -0,0 +1,41 @@
+opam-version: "2.0"
+synopsis: "Eio implementation for POSIX systems"
+description: "An Eio implementation for most Unix-like platforms"
+maintainer: ["anil@recoil.org"]
+authors: ["Anil Madhavapeddy" "Thomas Leonard"]
+license: "ISC"
+homepage: "https://github.com/ocaml-multicore/eio"
+doc: "https://ocaml-multicore.github.io/eio/"
+bug-reports: "https://github.com/ocaml-multicore/eio/issues"
+depends: [
+  "dune" {>= "3.7"}
+  "eio" {= version}
+  "iomux" {>= "0.2"}
+  "mdx" {>= "2.2.0" & with-test}
+  "fmt" {>= "0.8.9"}
+  "odoc" {with-doc}
+]
+build: [
+  ["dune" "subst"] {dev}
+  [
+    "dune"
+    "build"
+    "-p"
+    name
+    "-j"
+    jobs
+    "@install"
+    "@runtest" {with-test}
+    "@doc" {with-doc}
+  ]
+]
+dev-repo: "git+https://github.com/ocaml-multicore/eio.git"
+url {
+  src:
+    "https://github.com/ocaml-multicore/eio/releases/download/v0.10/eio-0.10.tbz"
+  checksum: [
+    "sha256=390f7814507b8133d6c25e3a67a742d731c7ca66252b287b1fb0e3ad4d10eecc"
+    "sha512=9c0c9088b178df9799aaae9deb803a802228f1329cbe452479c90e80a13985d9c364ea86ee14e4e759133940f9f6065c7e8ece509d176fb1e347c5320f00a494"
+  ]
+}
+x-commit-hash: "687ebf99a6ab10ce5d85f4a3335d8e2e94c2b875"
diff --git a/packages/eio_windows/eio_windows.0.10/opam b/packages/eio_windows/eio_windows.0.10/opam
new file mode 100644
index 00000000000..bc630baf53c
--- /dev/null
+++ b/packages/eio_windows/eio_windows.0.10/opam
@@ -0,0 +1,41 @@
+opam-version: "2.0"
+synopsis: "Eio implementation for Windows"
+description: "An Eio implementation using OCaml's Unix.select"
+maintainer: ["anil@recoil.org"]
+authors: ["Anil Madhavapeddy" "Thomas Leonard"]
+license: "ISC"
+homepage: "https://github.com/ocaml-multicore/eio"
+doc: "https://ocaml-multicore.github.io/eio/"
+bug-reports: "https://github.com/ocaml-multicore/eio/issues"
+depends: [
+  "dune" {>= "3.7"}
+  "eio" {= version}
+  "kcas" {>= "0.3.0" & with-test}
+  "alcotest" {>= "1.4.0" & with-test}
+  "odoc" {with-doc}
+]
+build: [
+  ["dune" "subst"] {dev}
+  [
+    "dune"
+    "build"
+    "-p"
+    name
+    "-j"
+    jobs
+    "@install"
+    "@runtest" {with-test}
+    "@doc" {with-doc}
+  ]
+]
+dev-repo: "git+https://github.com/ocaml-multicore/eio.git"
+url {
+  src:
+    "https://github.com/ocaml-multicore/eio/releases/download/v0.10/eio-0.10.tbz"
+  checksum: [
+    "sha256=390f7814507b8133d6c25e3a67a742d731c7ca66252b287b1fb0e3ad4d10eecc"
+    "sha512=9c0c9088b178df9799aaae9deb803a802228f1329cbe452479c90e80a13985d9c364ea86ee14e4e759133940f9f6065c7e8ece509d176fb1e347c5320f00a494"
+  ]
+}
+x-commit-hash: "687ebf99a6ab10ce5d85f4a3335d8e2e94c2b875"
+available: [os-family = "windows"]
diff --git a/packages/geojsone/geojsone.0.1.0/opam b/packages/geojsone/geojsone.0.1.0/opam
index 84c00194e6e..c8ff682f1c9 100644
--- a/packages/geojsone/geojsone.0.1.0/opam
+++ b/packages/geojsone/geojsone.0.1.0/opam
@@ -14,7 +14,7 @@ depends: [
   "mdx" {with-test}
   "ezjsonm" {with-test}
   "eio_main" {>= "0.6" & with-test}
-  "eio" {>= "0.6"}
+  "eio" {>= "0.6" & < "0.10"}
   "eio" {with-test & < "0.7"}
   "hex"
   "sexplib0"
diff --git a/packages/lwt_eio/lwt_eio.0.1/opam b/packages/lwt_eio/lwt_eio.0.1/opam
index 04de7d613e6..7710bce6a1d 100644
--- a/packages/lwt_eio/lwt_eio.0.1/opam
+++ b/packages/lwt_eio/lwt_eio.0.1/opam
@@ -10,7 +10,7 @@ bug-reports: "https://github.com/talex5/lwt_eio/issues"
 depends: [
   "ocaml"
   "dune" {>= "2.9"}
-  "eio"
+  "eio" {< "0.10"}
   "lwt"
   "mdx" {>= "1.10.0" & with-test}
   "eio_main" {with-test}
diff --git a/packages/rawlink-eio/rawlink-eio.2.1/opam b/packages/rawlink-eio/rawlink-eio.2.1/opam
index 89a7d61018b..5161b6b5bc1 100644
--- a/packages/rawlink-eio/rawlink-eio.2.1/opam
+++ b/packages/rawlink-eio/rawlink-eio.2.1/opam
@@ -13,7 +13,7 @@ depends: [
   "ocaml" {>= "5.0.0"}
   "dune" {>= "3.2"}
   "rawlink" {>= "2.1"}
-  "eio" {>= "0.4"}
+  "eio" {>= "0.4" & <"0.10"}
 ]
 depexts: [
   ["linux-headers"] {os-distribution = "alpine"}
diff --git a/packages/tls-eio/tls-eio.0.15.4/opam b/packages/tls-eio/tls-eio.0.15.4/opam
index 4468ab670e7..0e3047f995a 100644
--- a/packages/tls-eio/tls-eio.0.15.4/opam
+++ b/packages/tls-eio/tls-eio.0.15.4/opam
@@ -20,7 +20,7 @@ depends: [
   "mirage-crypto-rng" {>= "0.8.0"}
   "mirage-crypto-rng-eio" {>= "0.8.0" with-test}
   "x509" {>= "0.15.0"}
-  "eio" {>= "0.5"}
+  "eio" {>= "0.5" & <"0.10"}
   "eio_main" {>= "0.5" with-test}
   "mdx" {with-test}
 ]
diff --git a/packages/tls-eio/tls-eio.0.15.5/opam b/packages/tls-eio/tls-eio.0.15.5/opam
index bd81eaac15b..aea0c0f2a09 100644
--- a/packages/tls-eio/tls-eio.0.15.5/opam
+++ b/packages/tls-eio/tls-eio.0.15.5/opam
@@ -20,7 +20,7 @@ depends: [
   "mirage-crypto-rng" {>= "0.8.0"}
   "mirage-crypto-rng-eio" {>= "0.8.0" with-test}
   "x509" {>= "0.15.0"}
-  "eio" {>= "0.6"}
+  "eio" {>= "0.6" & <"0.10"}
   "eio_main" {>= "0.6" with-test}
   "mdx" {with-test}
 ]
diff --git a/packages/topojsone/topojsone.0.1.0/opam b/packages/topojsone/topojsone.0.1.0/opam
index dcd989db533..bdaea436830 100644
--- a/packages/topojsone/topojsone.0.1.0/opam
+++ b/packages/topojsone/topojsone.0.1.0/opam
@@ -15,6 +15,7 @@ depends: [
   "mdx" {>= "1.10.0" & with-test}
   "alcotest" {with-test}
   "ezjsonm" {with-test}
+  "eio" {>="0.7" & <"0.10"}
   "eio_main" {>= "0.7" & with-test}
   "odoc" {with-doc}
 ]