Hi Becky, Becky Bruce wrote: > Folks, > > We're going to be seeing more platforms with larger physical addresses > (PA) than virtual addresses (VA) supported in u-boot, and this kind of > ruins the current assumption inherent in much of u-boot that VA == > PA. On ppc, we've begin implementing the ability to actually > translate VAs to PAs and vice-versa. But this brings up the question > of, when I type an address on the command line, what exactly am I > specifying? Is that a virtual address, or a physical address? > > Wolfgang and I talked about this on IRC a bit earlier, and what we're > proposing is this:
[snip good discussion] > - Initially, a xlat (or insert better name here) command-line command > will be added to give you a PA given a VA, and vice-versa. How would xlat know which direction it is to translate? Thoughts: vtop(virtual) returns physical ptov(physical) returns virtual or (see below thought on 0v / 0p) xlat(0p1234) returns virtual xlat(0v1234) returns physical xlat(0x1234) returns physical (per convention from snipped discussion) I'm not wild about xlat doing dual duty (I'm not wild about vtop/ptov either but like it a little better). Shock but no awe. :-/ Question: Do we need a translation function? > - Going forward, commands will be extended to take either a VA or PA > at the command line, with the syntax for this TBD and per argument > (i.e. if a command takes multiple addresses, each one can be either a > va or pa, and they can be intermingled). The default will remain VA > if no modifier is specified. Thought: 0v6789ABCD is a virtual address (the value is interpreted as hex) 0p6789ABCD is a physical address Of course "v" and "p" should be accepted in either case. Kinda ugly, but fits into the 0x style conventions. I haven't looked at the number parsing code to see how hard it would be to squeeze this into it. > Note that unless your platform actually has enabled configs with VA != > PA (which is just MPC8641D at the moment, as far as I know), things > will look exactly the same as they always have. > > Comments? I'm looking for some consensus here before I spend my > weekend writing a whole bunch of code. Stuff face, write code. Does it get any better than that? ;-) > Cheers, > Becky Have a great Thanksgiving, gvb _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
