diff -Naur linux-5.8.orig/tools/perf/Documentation/Makefile linux-5.8/tools/perf/Documentation/Makefile
--- linux-5.8.orig/tools/perf/Documentation/Makefile	2020-08-06 12:44:43.255678224 +0300
+++ linux-5.8/tools/perf/Documentation/Makefile	2020-08-06 12:44:43.345678629 +0300
@@ -51,7 +51,7 @@
 ASCIIDOC_EXTRA += --unsafe -f asciidoc.conf
 ASCIIDOC_HTML = xhtml11
 MANPAGE_XSL = manpage-normal.xsl
-XMLTO_EXTRA =
+XMLTO_EXTRA = --skip-validation
 INSTALL?=install
 RM ?= rm -f
 DOC_REF = origin/man