Index: sys/compat/linprocfs/linprocfs.c
===================================================================
--- sys/compat/linprocfs/linprocfs.c
+++ sys/compat/linprocfs/linprocfs.c
@@ -60,6 +60,8 @@
 #include <sys/msg.h>
 #include <sys/mutex.h>
 #include <sys/namei.h>
+#include <sys/selinfo.h>
+#include <sys/pipe.h>
 #include <sys/proc.h>
 #include <sys/ptrace.h>
 #include <sys/resourcevar.h>
@@ -1348,6 +1350,19 @@
 }
 
 /*
+ * Filler function for proc/sys/fs/pipe-max-size
+ */
+static int
+linprocfs_dopipe_max_size(PFS_FILL_ARGS)
+{
+
+	sbuf_printf(sb, "%d\n", PIPE_SIZE);
+
+	return (0);
+}
+
+
+/*
  * Filler function for proc/sys/kernel/osrelease
  */
 static int
@@ -1777,6 +1792,12 @@
 
 	/* /proc/sys/... */
 	sys = pfs_create_dir(root, "sys", NULL, NULL, NULL, 0);
+
+	/* /proc/sys/fs/... */
+	dir = pfs_create_dir(sys, "fs", NULL, NULL, NULL, 0);
+	pfs_create_file(dir, "pipe-max-size", &linprocfs_dopipe_max_size,
+	    NULL, NULL, NULL, PFS_RD);
+
 	/* /proc/sys/kernel/... */
 	dir = pfs_create_dir(sys, "kernel", NULL, NULL, NULL, 0);
 	pfs_create_file(dir, "osrelease", &linprocfs_doosrelease,