Hi! > This patch implements the functionality of jumping between the kexeced > kernel and the original kernel. > > To support jumping between two kernels, before jumping to (executing) > the new kernel and jumping back to the original kernel, the devices > are put into quiescent state, and the state of devices and CPU is > saved. After jumping back from kexeced kernel and jumping to the new > kernel, the state of devices and CPU are restored accordingly. The > devices/CPU state save/restore code of software suspend is called to > implement corresponding function. > > To support jumping without reserving memory. One shadow backup page > (source page) is allocated for each page used by new (kexeced) kernel > (destination page). When do kexec_load, the image of new kernel is > loaded into source pages, and before executing, the destination pages > and the source pages are swapped, so the contents of destination pages > are backupped. Before jumping to the new (kexeced) kernel and after > jumping back to the original kernel, the destination pages and the > source pages are swapped too. > > A jump back protocol for kexec is defined and documented. It is an > extension to ordinary function calling protocol. So, the facility > provided by this patch can be used to call ordinary C function in real > mode. > > A set of flags for sys_kexec_load are added to control which state are > saved/restored before/after real mode code executing. For example, you > can specify the device state and FPU state are saved/restored > before/after real mode code executing. > > The states (exclude CPU state) save/restore code can be overridden > based on the "command" parameter of kexec jump. Because more states > need to be saved/restored by hibernating/resuming. > > Signed-off-by: Huang Ying <ying.huang@xxxxxxxxx> I'm not kexec hacker... but maybe this is in good enough state to be merged? It is useful on its own: kexec jump and back means we can dump system then continue running, for example... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
