diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -54,6 +54,7 @@
     REVIDX_FLAGS_ORDER,
     REVIDX_ISCENSORED,
     REVIDX_RAWTEXT_CHANGING_FLAGS,
+    REVIDX_SIDEDATA,
 )
 from .thirdparty import (
     attr,
@@ -75,6 +76,7 @@
 from .revlogutils import (
     deltas as deltautil,
     flagutil,
+    sidedata as sidedatautil,
 )
 from .utils import (
     storageutil,
@@ -95,6 +97,7 @@
 REVLOGV2_FLAGS
 REVIDX_ISCENSORED
 REVIDX_ELLIPSIS
+REVIDX_SIDEDATA
 REVIDX_EXTSTORED
 REVIDX_DEFAULT_FLAGS
 REVIDX_FLAGS_ORDER
@@ -389,6 +392,8 @@
         if self._mmaplargeindex and 'mmapindexthreshold' in opts:
             mmapindexthreshold = opts['mmapindexthreshold']
         self.hassidedata = bool(opts.get('side-data', False))
+        if self.hassidedata:
+            self._flagprocessors[REVIDX_SIDEDATA] = sidedatautil.processors
         self._sparserevlog = bool(opts.get('sparse-revlog', False))
         withsparseread = bool(opts.get('with-sparse-read', False))
         # sparse-revlog forces sparse-read
diff --git a/mercurial/revlogutils/flagutil.py b/mercurial/revlogutils/flagutil.py
--- a/mercurial/revlogutils/flagutil.py
+++ b/mercurial/revlogutils/flagutil.py
@@ -17,6 +17,7 @@
     REVIDX_FLAGS_ORDER,
     REVIDX_ISCENSORED,
     REVIDX_RAWTEXT_CHANGING_FLAGS,
+    REVIDX_SIDEDATA,
 )
 
 from .. import (
@@ -29,6 +30,7 @@
 REVIDX_ISCENSORED
 REVIDX_ELLIPSIS
 REVIDX_EXTSTORED
+REVIDX_SIDEDATA
 REVIDX_DEFAULT_FLAGS
 REVIDX_FLAGS_ORDER
 REVIDX_RAWTEXT_CHANGING_FLAGS
diff --git a/mercurial/revlogutils/sidedata.py b/mercurial/revlogutils/sidedata.py
--- a/mercurial/revlogutils/sidedata.py
+++ b/mercurial/revlogutils/sidedata.py
@@ -77,3 +77,9 @@
 def sidedatarawprocessor(rl, text):
     # side data modifies rawtext and prevent rawtext hash validation
     return False
+
+processors = (
+    sidedatareadprocessor,
+    sidedatawriteprocessor,
+    sidedatarawprocessor,
+)