>>> "Xu, Dongxiao" <dongxiao...@intel.com> 01/07/13 8:17 AM >>> > From: Jan Beulich [mailto:jbeul...@suse.com] > >>> On 20.12.12 at 02:23, "Xu, Dongxiao" <dongxiao...@intel.com> wrote: >> > 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. > >To make sure I understand you correctly, so do you mean the correct fix should >be > applied to libata driver, and make sure it DMA from/to correct place (for > example, > some memory allocated by DMA API), but not such certain field in a static > structure?
Yes. 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/
