On Wed, Aug 29, 2018 at 10:16:21PM +0800, Baoquan He wrote: > This was suggested by Kirill several months ago, I worked out several > patches to fix, then interrupted by other issues. So sort them out > now and post for reviewing. Thanks for doing this. > The current upstream kernel supports 5-level paging mode and supports > dynamically choosing paging mode during bootup according to kernel > image, hardware and kernel parameter setting. This flexibility brings > several issues for kexec/kdump: > 1) > Switching between paging modes, requires changes into target kernel. > It means you cannot kexec() 4-level paging kernel from 5-level paging > kernel if 4-level paging kernel doesn't include changes. > > 2) > Switching from 5-level paging to 4-level paging kernel would fail, if > kexec() put kernel image above 64TiB of memory. I'm not entirely sure that 64TiB is the limit here. Technically, 4-level paging allows to address 256TiB in 1-to-1 mapping. We just don't have machines with that wide physical address space (which don't support 5-level paging too). What is your reasoning about 64TiB limit? -- Kirill A. Shutemov _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
