diff --git a/tests/test-copies-chain-merge.t b/tests/test-copies-chain-merge.t
--- a/tests/test-copies-chain-merge.t
+++ b/tests/test-copies-chain-merge.t
@@ -51,7 +51,6 @@
 #if sidedata
   $ cat >> $HGRCPATH << EOF
   > [format]
-  > exp-use-side-data = yes
   > exp-use-copies-side-data-changeset = yes
   > EOF
 #endif
@@ -59,7 +58,6 @@
 #if pull
   $ cat >> $HGRCPATH << EOF
   > [format]
-  > exp-use-side-data = yes
   > exp-use-copies-side-data-changeset = yes
   > EOF
 #endif
@@ -67,7 +65,6 @@
 #if push
   $ cat >> $HGRCPATH << EOF
   > [format]
-  > exp-use-side-data = yes
   > exp-use-copies-side-data-changeset = yes
   > EOF
 #endif
@@ -75,7 +72,6 @@
 #if pull-upgrade
   $ cat >> $HGRCPATH << EOF
   > [format]
-  > exp-use-side-data = no
   > exp-use-copies-side-data-changeset = no
   > [experimental]
   > changegroup4 = yes
@@ -85,7 +81,6 @@
 #if push-upgrade
   $ cat >> $HGRCPATH << EOF
   > [format]
-  > exp-use-side-data = no
   > exp-use-copies-side-data-changeset = no
   > [experimental]
   > changegroup4 = yes
@@ -1652,7 +1647,6 @@
 #if upgraded
   $ cat >> $HGRCPATH << EOF
   > [format]
-  > exp-use-side-data = yes
   > exp-use-copies-side-data-changeset = yes
   > EOF
   $ hg debugformat -v
@@ -1687,7 +1681,6 @@
 #if upgraded-parallel
   $ cat >> $HGRCPATH << EOF
   > [format]
-  > exp-use-side-data = yes
   > exp-use-copies-side-data-changeset = yes
   > [experimental]
   > worker.repository-upgrade=yes
@@ -1743,7 +1736,6 @@
 #if pull-upgrade
   $ cat >> $HGRCPATH << EOF
   > [format]
-  > exp-use-side-data = yes
   > exp-use-copies-side-data-changeset = yes
   > [experimental]
   > changegroup4 = yes
@@ -1781,7 +1773,6 @@
 #if push-upgrade
   $ cat >> $HGRCPATH << EOF
   > [format]
-  > exp-use-side-data = yes
   > exp-use-copies-side-data-changeset = yes
   > [experimental]
   > changegroup4 = yes
diff --git a/tests/test-copies-in-changeset.t b/tests/test-copies-in-changeset.t
--- a/tests/test-copies-in-changeset.t
+++ b/tests/test-copies-in-changeset.t
@@ -445,8 +445,9 @@
   $ hg debugsidedata -m -- 0
   $ cat << EOF > .hg/hgrc
   > [format]
-  > exp-use-side-data = yes
   > exp-use-copies-side-data-changeset = no
+  > [experimental]
+  > revlogv2 = enable-unstable-format-and-corrupt-my-data
   > EOF
   $ hg debugupgraderepo --run --quiet --no-backup > /dev/null
   $ hg debugformat -v
diff --git a/tests/test-sidedata-exchange.t b/tests/test-sidedata-exchange.t
--- a/tests/test-sidedata-exchange.t
+++ b/tests/test-sidedata-exchange.t
@@ -8,12 +8,12 @@
 Pusher and pushed have sidedata enabled
 ---------------------------------------
 
-  $ hg init sidedata-source --config format.exp-use-side-data=yes
+  $ hg init sidedata-source --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data
   $ cat << EOF >> sidedata-source/.hg/hgrc
   > [extensions]
   > testsidedata=$TESTDIR/testlib/ext-sidedata-5.py
   > EOF
-  $ hg init sidedata-target --config format.exp-use-side-data=yes
+  $ hg init sidedata-target --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data
   $ cat << EOF >> sidedata-target/.hg/hgrc
   > [extensions]
   > testsidedata=$TESTDIR/testlib/ext-sidedata-5.py
@@ -71,12 +71,12 @@
 ---------------------------------------
 
   $ rm -rf sidedata-source sidedata-target
-  $ hg init sidedata-source --config format.exp-use-side-data=yes
+  $ hg init sidedata-source --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data
   $ cat << EOF >> sidedata-source/.hg/hgrc
   > [extensions]
   > testsidedata=$TESTDIR/testlib/ext-sidedata-5.py
   > EOF
-  $ hg init sidedata-target --config format.exp-use-side-data=yes
+  $ hg init sidedata-target --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data
   $ cat << EOF >> sidedata-target/.hg/hgrc
   > [extensions]
   > testsidedata=$TESTDIR/testlib/ext-sidedata-5.py
@@ -138,12 +138,12 @@
 --------------------------------------------
 
   $ rm -rf sidedata-source sidedata-target
-  $ hg init sidedata-source --config format.exp-use-side-data=yes
+  $ hg init sidedata-source --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data
   $ cat << EOF >> sidedata-source/.hg/hgrc
   > [extensions]
   > testsidedata=$TESTDIR/testlib/ext-sidedata-5.py
   > EOF
-  $ hg init sidedata-target --config format.exp-use-side-data=no
+  $ hg init sidedata-target --config experimental.revlogv2=no
   $ cd sidedata-source
   $ echo a > a
   $ echo b > b
@@ -186,12 +186,12 @@
 --------------------------------------------
 
   $ rm -rf sidedata-source sidedata-target
-  $ hg init sidedata-source --config format.exp-use-side-data=yes
+  $ hg init sidedata-source --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data
   $ cat << EOF >> sidedata-source/.hg/hgrc
   > [extensions]
   > testsidedata=$TESTDIR/testlib/ext-sidedata-5.py
   > EOF
-  $ hg init sidedata-target --config format.exp-use-side-data=no
+  $ hg init sidedata-target --config experimental.revlogv2=no
   $ cd sidedata-source
   $ echo a > a
   $ echo b > b
@@ -239,8 +239,8 @@
 (Push) Target has strict superset of the source
 -----------------------------------------------
 
-  $ hg init source-repo --config format.exp-use-side-data=yes
-  $ hg init target-repo --config format.exp-use-side-data=yes
+  $ hg init source-repo --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data
+  $ hg init target-repo --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data
   $ cat << EOF >> target-repo/.hg/hgrc
   > [extensions]
   > testsidedata=$TESTDIR/testlib/ext-sidedata.py
@@ -311,12 +311,12 @@
 target.
 
   $ rm -rf source-repo target-repo
-  $ hg init source-repo --config format.exp-use-side-data=yes
+  $ hg init source-repo --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data
   $ cat << EOF >> source-repo/.hg/hgrc
   > [extensions]
   > testsidedata3=$TESTDIR/testlib/ext-sidedata-3.py
   > EOF
-  $ hg init target-repo --config format.exp-use-side-data=yes
+  $ hg init target-repo --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data
   $ cat << EOF >> target-repo/.hg/hgrc
   > [extensions]
   > testsidedata4=$TESTDIR/testlib/ext-sidedata-4.py
@@ -412,8 +412,8 @@
 -----------------------------------------------
 
   $ rm -rf source-repo target-repo
-  $ hg init source-repo --config format.exp-use-side-data=yes
-  $ hg init target-repo --config format.exp-use-side-data=yes
+  $ hg init source-repo --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data
+  $ hg init target-repo --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data
   $ cat << EOF >> target-repo/.hg/hgrc
   > [extensions]
   > testsidedata=$TESTDIR/testlib/ext-sidedata.py
diff --git a/tests/test-sidedata.t b/tests/test-sidedata.t
--- a/tests/test-sidedata.t
+++ b/tests/test-sidedata.t
@@ -10,7 +10,7 @@
   > testsidedata=$TESTDIR/testlib/ext-sidedata.py
   > EOF
 
-  $ hg init test-sidedata --config format.exp-use-side-data=yes
+  $ hg init test-sidedata --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data
   $ cd test-sidedata
   $ echo aaa > a
   $ hg add a
@@ -48,7 +48,7 @@
 Check that we can upgrade to sidedata
 -------------------------------------
 
-  $ hg init up-no-side-data --config format.exp-use-side-data=no
+  $ hg init up-no-side-data --config experimental.revlogv2=no
   $ hg debugformat -v -R up-no-side-data
   format-variant     repo config default
   fncache:            yes    yes     yes
@@ -64,7 +64,7 @@
   compression:        zlib   zlib    zlib (no-zstd !)
   compression:        zstd   zstd    zstd (zstd !)
   compression-level:  default default default
-  $ hg debugformat -v -R up-no-side-data --config format.exp-use-side-data=yes
+  $ hg debugformat -v -R up-no-side-data --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data
   format-variant     repo config default
   fncache:            yes    yes     yes
   dotencode:          yes    yes     yes
@@ -79,12 +79,12 @@
   compression:        zlib   zlib    zlib (no-zstd !)
   compression:        zstd   zstd    zstd (zstd !)
   compression-level:  default default default
-  $ hg debugupgraderepo -R up-no-side-data --config format.exp-use-side-data=yes > /dev/null
+  $ hg debugupgraderepo -R up-no-side-data --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data > /dev/null
 
 Check that we can downgrade from sidedata
 -----------------------------------------
 
-  $ hg init up-side-data --config format.exp-use-side-data=yes
+  $ hg init up-side-data --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data
   $ hg debugformat -v -R up-side-data
   format-variant     repo config default
   fncache:            yes    yes     yes
@@ -100,7 +100,7 @@
   compression:        zlib   zlib    zlib (no-zstd !)
   compression:        zstd   zstd    zstd (zstd !)
   compression-level:  default default default
-  $ hg debugformat -v -R up-side-data --config format.exp-use-side-data=no
+  $ hg debugformat -v -R up-side-data --config experimental.revlogv2=no
   format-variant     repo config default
   fncache:            yes    yes     yes
   dotencode:          yes    yes     yes
@@ -115,4 +115,4 @@
   compression:        zlib   zlib    zlib (no-zstd !)
   compression:        zstd   zstd    zstd (zstd !)
   compression-level:  default default default
-  $ hg debugupgraderepo -R up-side-data --config format.exp-use-side-data=no > /dev/null
+  $ hg debugupgraderepo -R up-side-data --config experimental.revlogv2=no > /dev/null
diff --git a/tests/test-upgrade-repo.t b/tests/test-upgrade-repo.t
--- a/tests/test-upgrade-repo.t
+++ b/tests/test-upgrade-repo.t
@@ -1448,13 +1448,13 @@
 
 #endif
 
-Check upgrading to a side-data revlog
--------------------------------------
+Check upgrading to a revlog format supporting sidedata
+------------------------------------------------------
 
 upgrade
 
   $ hg debugsidedata -c 0
-  $ hg --config format.exp-use-side-data=yes debugupgraderepo --run  --no-backup --config "extensions.sidedata=$TESTDIR/testlib/ext-sidedata.py" --quiet
+  $ hg --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data debugupgraderepo --run  --no-backup --config "extensions.sidedata=$TESTDIR/testlib/ext-sidedata.py" --quiet
   upgrade will perform the following actions:
   
   requirements
@@ -1462,8 +1462,8 @@
      preserved: dotencode, fncache, generaldelta, revlog-compression-zstd, sparserevlog, store (zstd no-rust !)
      preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlog-compression-zstd, sparserevlog, store (rust !)
      removed: revlogv1
-     added: exp-revlogv2.2, exp-sidedata-flag (zstd !)
-     added: exp-revlogv2.2, exp-sidedata-flag, sparserevlog (no-zstd !)
+     added: exp-revlogv2.2 (zstd !)
+     added: exp-revlogv2.2, sparserevlog (no-zstd !)
   
   processed revlogs:
     - all-filelogs
@@ -1488,7 +1488,6 @@
   $ cat .hg/requires
   dotencode
   exp-revlogv2.2
-  exp-sidedata-flag
   fncache
   generaldelta
   persistent-nodemap (rust !)
@@ -1502,14 +1501,14 @@
 
 downgrade
 
-  $ hg debugupgraderepo --config format.exp-use-side-data=no --run --no-backup --quiet
+  $ hg debugupgraderepo --config experimental.revlogv2=no --run --no-backup --quiet
   upgrade will perform the following actions:
   
   requirements
      preserved: dotencode, fncache, generaldelta, sparserevlog, store (no-zstd !)
      preserved: dotencode, fncache, generaldelta, revlog-compression-zstd, sparserevlog, store (zstd no-rust !)
      preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlog-compression-zstd, sparserevlog, store (rust !)
-     removed: exp-revlogv2.2, exp-sidedata-flag
+     removed: exp-revlogv2.2
      added: revlogv1
   
   processed revlogs:
@@ -1546,8 +1545,8 @@
 upgrade from hgrc
 
   $ cat >> .hg/hgrc << EOF
-  > [format]
-  > exp-use-side-data=yes
+  > [experimental]
+  > revlogv2=enable-unstable-format-and-corrupt-my-data
   > EOF
   $ hg debugupgraderepo --run --no-backup --quiet
   upgrade will perform the following actions:
@@ -1557,7 +1556,7 @@
      preserved: dotencode, fncache, generaldelta, revlog-compression-zstd, sparserevlog, store (zstd no-rust !)
      preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlog-compression-zstd, sparserevlog, store (rust !)
      removed: revlogv1
-     added: exp-revlogv2.2, exp-sidedata-flag
+     added: exp-revlogv2.2
   
   processed revlogs:
     - all-filelogs
@@ -1582,7 +1581,6 @@
   $ cat .hg/requires
   dotencode
   exp-revlogv2.2
-  exp-sidedata-flag
   fncache
   generaldelta
   persistent-nodemap (rust !)