On Mon, Aug 05, 2019 at 10:50:30AM -0700, Thomas Garnier wrote: > I saw that %rdx was used for temporary usage and restored before the > end so I assumed that it was not an option. PUSH_AND_CLEAR_REGS saves all regs earlier so I think you should be able to use others. Like SAVE_AND_SWITCH_TO_KERNEL_CR3/RESTORE_CR3, for example, uses %r15 and %r14. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.