>>> On 20.12.12 at 02:23, "Xu, Dongxiao" <dongxiao...@intel.com> wrote: > Sorry, maybe I am still not describing this issue clearly.
No, at least I understood you the way you re-describe below. > Take the libata case as an example, the static DMA buffer locates > (dev->link->ap->sector_buf , here we use Data Structure B in the graph) in > the following structure: > > -------------------------------------Page boundary > <Data Structure A> > <Data Structure B> > -------------------------------------Page boundary > <Data Structure B (cross page)> > <Data Structure C> > -------------------------------------Page boundary > > Where Structure B is our DMA target. > > For Data Structure B, we didn't care about the simultaneous access, either > lock or sync function will take care of it. > What we are not sure is "read/write of A and C from other processor". As we > will have memory copy for the pages, and at the same time, other CPU may > access A/C. The question is whether what libata does here is valid in the first place - fill an SG list entry with something that crosses a page boundary and is not a compound page. Jan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
