On Mon, Nov 18, 2013 at 5:32 PM, H. Peter Anvin <hpa@xxxxxxxxx> wrote: > On 11/15/2013 10:30 AM, Vivek Goyal wrote: >> >> And IOMMU support is very flaky with kdump. And IOMMU's can be turned >> off at command line. And that would force one to remove crahkernel_low=0. >> So change of one command line option forces change of another. It is >> complicated. >> >> Also there are very few systems which work with IOMMU on. A lot more >> which work without IOMMU. We have all these DMAR issues and still nobody >> has been able to address IOMMU issues properly. >> > > Why do we need such a big bounce buffer for kdump swiotlb anyway? > Surely the vast majority of all dump devices don't need it, so it is > there for completeness, no? Yes, because normal path will need that 64M+32k default. We may reduce that amount to 16M or 18M and in second kernel let allocate less for swiotlb. Thanks Yinghai -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>