[legacy] Allocate legacy driver .bss-like segments at probe time

Some legacy drivers use large static allocations for transmit and
receive buffers.  To avoid bloating the .bss segment, we currently
implement these as a single common symbol named "_shared_bss" (which
is permissible since only one legacy driver may be active at any one
time).

Switch to dynamic allocation of these .bss-like segments, to avoid the
requirement for using common symbols.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/net/sis900.c

@@ -65,12 +65,13 @@ static unsigned int cur_phy;
 
 static unsigned int cur_rx;
 
-struct {
+struct sis900_bss {
     BufferDesc txd;
     BufferDesc rxd[NUM_RX_DESC];
     unsigned char txb[TX_BUF_SIZE];
     unsigned char rxb[NUM_RX_DESC * RX_BUF_SIZE];
-} sis900_bufs __shared;
+};
+#define sis900_bufs NIC_FAKE_BSS ( struct sis900_bss )
 #define txd sis900_bufs.txd
 #define rxd sis900_bufs.rxd
 #define txb sis900_bufs.txb
@@ -1291,7 +1292,7 @@ PCI_ROM(0x1039, 0x7016, "sis7016", "SIS7016", 0),
 PCI_DRIVER ( sis900_driver, sis900_nics, PCI_NO_CLASS );
 
 DRIVER ( "SIS900", nic_driver, pci_driver, sis900_driver,
-	 sis900_probe, sis900_disable );
+	 sis900_probe, sis900_disable, sis900_bufs );
 
 /*
  * Local variables: