37  * By default, we direct-map starting at 2GB, in order to allow the
38  * maximum size direct-map window (2GB) to match the maximum amount of
39  * memory (2GB) that can be present on SABLEs. But that limits the
40  * floppy to DMA only via the scatter/gather window set up for 8MB
41  * ISA DMA, since the maximum ISA DMA address is 2GB-1.
62  * NOTE: Herein lie back-to-back mb instructions.  They are magic. 
90 	} window[2];
107  *  3 3|3 3 2 2|2 2 2 2|2 2 2 2|1 1 1 1|1 1 1 1|1 1 
108  *  3 2|1 0 9 8|7 6 5 4|3 2 1 0|9 8 7 6|5 4 3 2|1 0 9 8|7 6 5 4|3 2 1 0
115  * 	 7:2	Register number
119  *  3 3|3 3 2 2|2 2 2 2|2 2 2 2|1 1 1 1|1 1 1 1|1 1 
120  *  3 2|1 0 9 8|7 6 5 4|3 2 1 0|9 8 7 6|5 4 3 2|1 0 9 8|7 6 5 4|3 2 1 0
129  *	 7:2	register number
136  *	doesn't get shifted by 2 bits as we want to "drop" the bottom two
194 		mb();  in conf_read()
196 	mb();  in conf_read()
202 	mb();  in conf_read()
206 	mb();  in conf_read()
207 	mb();  /* magic */  in conf_read()
219 		mb();  in conf_read()
223 	mb();  in conf_read()
228 		mb();  in conf_read()
246 		mb();  in conf_write()
248 	mb();  in conf_write()
254 	mb();  in conf_write()
258 	mb();  in conf_write()
259 	mb();  /* magic */  in conf_write()
270 		mb();  in conf_write()
274 	mb();  in conf_write()
279 		mb();  in conf_write()
362 	mb();  in t2_sg_map_window2()
426 		mb();	  in t2_init_arch()
455 	 * Window 2 is scatter/gather (for ISA).  in t2_init_arch()
466 	*(vulp)T2_HAE_1 = 0; mb(); /* Sparse MEM HAE */  in t2_init_arch()
467 	*(vulp)T2_HAE_2 = 0; mb(); /* Sparse I/O HAE */  in t2_init_arch()
468 	*(vulp)T2_HAE_3 = 0; mb(); /* Config Space HAE */  in t2_init_arch()
479 	*(vulp)T2_HAE_4 = 0; mb();  in t2_init_arch()
494 	mb();  in t2_kill_arch()
501 	mb();  in t2_kill_arch()
514 	mb();  in t2_pci_tbi()
519 	mb();  in t2_pci_tbi()
543 	mb();  in t2_clear_errors()
544 	mb();  /* magic */  in t2_clear_errors()
565 	mb();  in t2_machine_check()
566 	mb();  /* magic */  in t2_machine_check()
573 	mb();  in t2_machine_check()
605 		    mb();  in t2_machine_check()
609 			mb();  in t2_machine_check()