On 11/15/2018 4:47 PM, Bhupesh Sharma wrote: > Adding 'page_offset_base' to the vmcoreinfo can be specially useful for > live-debugging of a running kernel via user-space utilities > like makedumpfile (see [1]). I agree. > Recently, I saw an issue with the 'makedumpfile' utility (see [2] for > details), whose live debugging feature is broken with newer kernels > (I tested the same with 4.19-rc8+ kernel), as KCORE_REMAP segments were > added to kcore, thus leading to an additional sections in the same, and > makedumpfile is not longer able to determine the start of direct > mapping of all physical memory, as it relies on traversing the PT_LOAD > segments inside kcore and using the last PT_LOAD segment > to determine the start of direct mapping. Actually, the KCORE_REMAP segments were already removed from kcore by commit bf904d2762ee ("x86/pti/64: Remove the SYSCALL64 entry trampoline") and kcore's program headers got back to the previous ones, but this fact shows that they are changeable. So I think that if we have this NUMBER(page_offset_base) in vmcoreinfo for x86_64, user-space tools (especially makedumpfile) would become more stable against changes in kcore and vmcore, rather than depending on their PT_LOAD values. Thanks, Kazu _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec