On Mon, Jan 7, 2013 at 6:22 PM, Eric W. Biederman <ebied...@xmission.com> wrote: > Yinghai I sat down and read your patch and the approach you are taking > is totally wrong.
Thanks for check the patch, did you check v3? > > The problem is that swiotlb_init() in lib/swiotlb.c does not know how to > fail without panic'ing the system. I did not put panic in swiotlb, now I put panic in amd_iommu ops init when it need extra swiotlb for unhandled devices by AMD IOMMU. > > Which leaves two valid approaches. > - Create a variant of swiotlb_init that can fail for use on x86 and > handle the failure. > - Delay initializing the swiotlb until someone actually needs a mapping > from it. > > Delaying the initialization of the swiotlb is out because the code > needs an early memory allocation to get a large chunk of contiguous > memory for the bounce buffers. ok. > > Which means the panics that occurr in swiotlb_init() need to be delayed > until someone something actually needs bounce buffers from the swiotlb. > > Although arguably what should actually happen instead of panic() is that > swiotlb_map_single should simply fail early when it was not possible to > preallocate bounce buffers. do you mean: actually needed dma buffer is much less than swiotlb buffer aka 64M? Yinghai -- 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/