Use the magic of common symbols to allow struct dev to effectively grow at

link time to accommodate whatever bus objects are included.

src/include/dev.h

@@ -3,11 +3,6 @@
 
 #include "stdint.h"
 
-/* Bus types */
-#include "pci.h"
-#include "eisa.h"
-#include "mca.h"
-
 /* Device types */
 #include "nic.h"
 
@@ -18,8 +13,7 @@ struct dev_id {
 	uint8_t		bus_type;
 #define	PCI_BUS_TYPE	1
 #define	ISA_BUS_TYPE	2
-#define EISA_BUS_TYPE	3
-#define MCA_BUS_TYPE	4
+#define MCA_BUS_TYPE	3
 } __attribute__ ((packed));
 
 /* Dont use sizeof, that will include the padding */
@@ -29,18 +23,25 @@ struct dev {
 	struct dev_operations *dev_op;
 	const char *name;
 	struct dev_id	devid;	/* device ID string (sent to DHCP server) */
-	/* All possible bus types */
-	union {
-		struct pci_device	pci;
-		struct eisa_device	eisa;
-		struct mca_device	mca;
-	};
+	/* Pointer to bus information for device.  Whatever sets up
+	 * the struct dev must make sure that this points to a buffer
+	 * large enough for the required struct <bus>_device.
+	 */
+	void *bus;
 	/* All possible device types */
 	union {
 		struct nic	nic;
 	};
 };
 
+/*
+ * Macro to help create a common symbol with enough space for any
+ * struct <bus>_device.
+ *
+ * Use as e.g. DEV_BUS(struct pci_device);
+ */
+#define DEV_BUS(datatype,symbol) datatype symbol __asm__ ( "_dev_bus" );
+
 struct dev_operations {
 	void ( *disable ) ( struct dev * );
 	void ( *print_info ) ( struct dev * );

src/include/eisa.h

@@ -27,6 +27,7 @@
  */
 struct dev;
 struct eisa_device {
+	char *magic; /* must be first */
 	struct dev *dev;
 	unsigned int slot;
 	uint16_t ioaddr;

src/include/mca.h

@@ -28,6 +28,7 @@
  */
 struct dev;
 struct mca_device {
+	char *magic; /* must be first */
 	struct dev *dev;
 	unsigned int slot;
 	unsigned char pos[8];

src/include/pci.h

@@ -232,13 +232,13 @@
 #define PCI_MSI_ADDRESS_HI	8	/* Upper 32 bits (if PCI_MSI_FLAGS_64BIT set) */
 #define PCI_MSI_DATA_32		8	/* 16 bits of data for 32-bit devices */
 #define PCI_MSI_DATA_64		12	/* 16 bits of data for 64-bit devices */
-
 /*
  * A physical PCI device
  *
  */
 struct dev;
 struct pci_device {
+	char *			magic; /* must be first */
 	struct dev *		dev;
 	uint32_t		membase;	/* BAR 1 */
 	uint32_t		ioaddr;		/* first IO BAR */