Merged mcb30-realmode-redesign back to HEAD

src/arch/i386/include/virtaddr.h

@@ -0,0 +1,85 @@
+#ifndef VIRTADDR_H
+#define VIRTADDR_H
+
+/* Segment selectors as used in our protected-mode GDTs.
+ *
+ * Don't change these unless you really know what you're doing.
+ */
+#define PHYSICAL_CS 0x08
+#define PHYSICAL_DS 0x10
+#define VIRTUAL_CS 0x18
+#define VIRTUAL_DS 0x20
+#define LONG_CS 0x28
+#define LONG_DS 0x30
+
+#ifndef ASSEMBLY
+
+#include "stdint.h"
+
+#ifndef KEEP_IT_REAL
+
+/*
+ * Without -DKEEP_IT_REAL, we are in 32-bit protected mode with a
+ * fixed link address but an unknown physical start address.  Our GDT
+ * sets up code and data segments with an offset of virt_offset, so
+ * that link-time addresses can still work.
+ *
+ */
+
+/* C-callable function prototypes */
+
+extern void relocate_to ( uint32_t new_phys_addr );
+
+/* Variables in virtaddr.S */
+extern unsigned long virt_offset;
+
+/*
+ * Convert between virtual and physical addresses
+ *
+ */
+static inline unsigned long virt_to_phys ( volatile const void *virt_addr ) {
+	return ( ( unsigned long ) virt_addr ) + virt_offset;
+}
+
+static inline void * phys_to_virt ( unsigned long phys_addr ) {
+	return ( void * ) ( phys_addr - virt_offset );
+}
+
+#else /* KEEP_IT_REAL */
+
+/*
+ * With -DKEEP_IT_REAL, we are in 16-bit real mode with fixed link
+ * addresses and a segmented memory model.  We have separate code and
+ * data segments.
+ *
+ * Because we may be called in 16-bit protected mode (damn PXE spec),
+ * we cannot simply assume that physical = segment * 16 + offset.
+ * Instead, we have to look up the physical start address of the
+ * segment in the !PXE structure.  We have to assume that
+ * virt_to_phys() is called only on pointers within the data segment,
+ * because nothing passes segment information to us.
+ *
+ * We don't implement phys_to_virt at all, because there will be many
+ * addresses that simply cannot be reached via a virtual address when
+ * the virtual address space is limited to 64kB!
+ */
+
+static inline unsigned long virt_to_phys ( volatile const void *virt_addr ) {
+	/* Cheat: just for now, do the segment*16+offset calculation */
+	uint16_t ds;
+
+	__asm__ ( "movw %%ds, %%ax" : "=a" ( ds ) : );
+	return ( 16 * ds + ( ( unsigned long ) virt_addr ) );
+}
+
+/* Define it as a deprecated function so that we get compile-time
+ * warnings, rather than just the link-time errors.
+ */
+extern void * phys_to_virt ( unsigned long phys_addr )
+     __attribute__ ((deprecated));
+
+#endif /* KEEP_IT_REAL */
+
+#endif /* ASSEMBLY */
+
+#endif /* VIRTADDR_H */