x86: allow early use of fixmaps

As a prerequisite for adding an EHCI debug port based console
implementation, set up the page tables needed for (a sub-portion of)
the fixmaps together with other boot time page table construction.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Keir Fraser <keir@xen.org>

1 files changed, 24 insertions, 0 deletions

diff --git a/xen/include/xen/const.h b/xen/include/xen/const.h
new file mode 100644
index 0000000000..0d5b2c64f5
--- /dev/null
+++ b/xen/include/xen/const.h
@@ -0,0 +1,24 @@
+/* const.h: Macros for dealing with constants.  */
+
+#ifndef __XEN_CONST_H__
+#define __XEN_CONST_H__
+
+/* Some constant macros are used in both assembler and
+ * C code.  Therefore we cannot annotate them always with
+ * 'UL' and other type specifiers unilaterally.  We
+ * use the following macros to deal with this.
+ *
+ * Similarly, _AT() will cast an expression with a type in C, but
+ * leave it unchanged in asm.
+ */
+
+#ifdef __ASSEMBLY__
+#define _AC(X,Y)	X
+#define _AT(T,X)	X
+#else
+#define __AC(X,Y)	(X##Y)
+#define _AC(X,Y)	__AC(X,Y)
+#define _AT(T,X)	((T)(X))
+#endif
+
+#endif /* __XEN_CONST_H__ */