On Sat, Feb 02, 2019 at 06:16:59PM +0100, Christoph Hellwig wrote: > On Fri, Feb 01, 2019 at 03:15:59PM -0800, Darren Hart wrote: > > On Tue, Jan 29, 2019 at 08:34:09AM +0100, Christoph Hellwig wrote: > > > For some odd reason dell_rbu actually seems to want the physical and > > > not a bus address for the allocated buffer. Lets assume that actually > > > is correct given that it is BIOS-related and that is a good source > > > of insanity. In that case we should not use dma_alloc_coherent with > > > a NULL device to allocate memory, but use GFP_DMA32 to stay under > > > the 32-bit BIOS limit. > > > > + Mario re bios related physical address - is Christoph's assumption > > correct? > > > > Christoph, did you observe a failure? If so, we should probably also > > tag for stable. > > No, I've been auditing for DMA API (ab-)users that don't pass a > struct device. Generally the fix was to just pass a struct device > that is easily available. But dell_rbu doesn't actually seem to > be a "device" in the traditional sense, and the way it uses the > DMA API is really, really odd - it first does a virt_to_phys on > memory allocated from the page allocator (so works with physical > addresses in that case) and the retries with a dma_alloc_coherent > with a NULL argument, which in no way is guaranteed to you give > you something else, although for the current x86 implementation > will give you the equivalent of a GFP_DMA32 page allocator allocation > plus virt_to_phys. > Thanks Christoph, merged to for-next. -- Darren Hart VMware Open Source Technology Center
