On Mon, Mar 11, 2013 at 12:59:44PM -0700, H. Peter Anvin wrote: > On 03/11/2013 12:22 PM, Vivek Goyal wrote: > > > > So always reserving memory at highest address will break all the cases > > which work without iommu and rely on swiotlb. I think first we need > > to make sure that kdump works reliably with iommu on, and then try > > to move to always reserving memory at higest possible address. > > > > We should clearly always reserve an swiotlb window, *or*, probably much > better, teach the kdump kernel to *make* an swiotlb window (by having a > memory buffer in its reserved memory area into which it copies a chunk > of low memory, just as we do for the bottom megabyte. If we are already > in low memory that buffer becomes the swiotlb window, no copy necessary.)
This sounds like a good idea. It will require exporting how much memory should be needed for swiotlb. And then kexec-tools should be able to backup that memory area and make that memory available to second kernel. Thanks Vivek -- 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/
