v4.19.13 snapshot.
diff --git a/arch/x86/kernel/eisa.c b/arch/x86/kernel/eisa.c
new file mode 100644
index 0000000..e8c8c5d
--- /dev/null
+++ b/arch/x86/kernel/eisa.c
@@ -0,0 +1,25 @@
+/*
+ * EISA specific code
+ *
+ * This file is licensed under the GPL V2
+ */
+#include <linux/ioport.h>
+#include <linux/eisa.h>
+#include <linux/io.h>
+
+#include <xen/xen.h>
+
+static __init int eisa_bus_probe(void)
+{
+ void __iomem *p;
+
+ if (xen_pv_domain() && !xen_initial_domain())
+ return 0;
+
+ p = ioremap(0x0FFFD9, 4);
+ if (p && readl(p) == 'E' + ('I' << 8) + ('S' << 16) + ('A' << 24))
+ EISA_bus = 1;
+ iounmap(p);
+ return 0;
+}
+subsys_initcall(eisa_bus_probe);