On Saturday 23 June 2007 00:19:51 Alan Cox wrote: > > YH do you think you can look at simply reserving a portion of the iommu? > > And having the kexec on panic kernel use the reserved portion? > > How about simply reserving all of it for the base kernel and using soft > iommu for the panic kernel, its hardly high performance criticial at this > point.
The kdump kernel should be normally all <4GB anyways. You won't need any IOMMU for its IO unless you O_DIRECT/sendfile out of /proc/kcore. Just don't do that (but I suspect it won't work anyways) If it's not then swiotlb will also not work because it won't get any memory <4GB. But I doubt this was YH's problem - the panic kernel memory is always reserved and there shouldn't be any ongoing DMAs in this area anyways. And what happens outside the kdump kernel shouldn't matter. I suspect he rather saw problems with non kdump kexec where we can just shut down the GART properly beforehand. -Andi - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
