On 10/15/2012 09:52 PM, Benjamin Herrenschmidt wrote: >> >> I do have an is_write parameter to translate, in fact I added it in >> order to implement the spapr iommu. Or do you mean something else? > > Hrm, sort of. "is_write" means you can only express RO vs RW. Two > parameter for read and write allow to express WO. The only difference is > going to be if something does one translate for several R and W. > > Not a huge deal, since mostly translate is used for atomic accesses so > one translate = one access... except with map. It's useful to > differenciate the map with 3 states: RO, WO, RW.
address_space_rw() and address_space_map() can only by used for one direction at the time (the first due to its API, the second because of the need to bounce sometimes), so the current ->translate() signature is okay for that. We can consider dropping the is_write parameter and replacing it with permission bits in IOMMUTLBEntry, I think it's a little more elegant (but no real advantage unless we start caching IOMMUTLBEntries). -- error compiling committee.c: too many arguments to function
