jkh weird problem (reading pci device memory)

[John-Mark Gurney]

Niki Denev wrote this message on Sat, Aug 12, 2006 at 11:42 +0300:
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> John Baldwin wrote:
> > On Saturday 05 August 2006 10:06, Niki Denev wrote:
> >> 	for(i=0; i < sizeof(config_table_t); i++) {
> >> 		r =  bus_space_read_1(sc->bar.tag, sc->bar.hdl, i);
> >> 		*((u_int8_t *)&sc->cfg_table + i) =  r;
> >> 		}
> > 
> > Note that you can replace this with:
> > 
> > 	bus_space_read_multi_1(sc->bar.tag, sc->bar.hdl, 0,
> > 	    (u_int8_t *)&sc->cfg_table, sizeof(config_table_t));
> > 
> 
> I can't understand why the code above gives me different results.
> i.e.:
> 
> 	for(i=0; i < sizeof(config_table_t); i++) {
> 		*((u_int8_t *)&sc->cfg_table + i) =  bus_read_1(sc->res, i);
> 	}
> 	printf("cfg_table signature : %08X\n", sc->cfg_table.signature);
> 
> This prints : cfg_table signaature 0xEFEFFEFE, which is the correct signature
> that should be read from the card.
> 
> But this code :
> 
> 	bus_read_multi_1(sc->res, 0, (u_int8_t *)&sc->cfg_table, sizeof(config_table_t));
> 	printf("cfg_table signature : %08X\n", sc->cfg_table.signature);
> 
> prints : cfg_table signature 0xFEFEFEFE
> which is not correct...
> 
> Shouldn't the above examples do exactly the same thing?

No, read_multi reads from the same location every time..  This is for
things like a FIFO where the value can change each time, you want
bus_read_region_1...   Read the bus_space(9) man page for more info
about the differences between the two...

http://www.freebsd.org/cgi/man.cgi?query=bus_space&apropos=0&sektion=0&manpath=FreeBSD+6.1-RELEASE&format=html

-- 
  John-Mark Gurney				Voice: +1 415 225 5579

     "All that I will do, has been done, All that I have, has not."