On Tuesday, 17 July 2007 14:48, Huang, Ying wrote: > On Tue, 2007-07-17 at 01:13 -0700, david@xxxxxxx wrote: > > however, since the resume designed for ACPI won't work would the following > > approach work > > > > 1. boot one kernel > > 2. setup a kexec the same way you would for hibernate > > 3. kexec to the new kernel > > 4. overwrite the memory of the first kernel > > 5. kexec 'back' to the main kernel that has now been overwritten by what was saved? > > > > as part of this question, when you do a kexec, how does the kernel that > > you are doing the kexec to know what to run next? > > For kernel in 3 that do kexec, the devices and CPU state are saved into > memory before executing the new kernel. So when jumping back, the > control will continue from kexec point. If the memory image of main > kernel is restored from disk, the devices and CPU state in memory is > restored too. Before jumping back in 5, the devices are put in the known > state, after jumping back, the devices and CPU state is restored. If the > "kexec -j" is used to trigger the kexec in 3, the system will continue > with "kexec -j" exiting with exit code 0. > > > it needs to do some initialization first before it starts running normal > > things, and at that point it the move back doesn't look for init like a > > normal kernel boot (or the system would effectivly boot instead of picking > > up where it left off) > > I think the early initialization can be done in a initramfs. At that > point, the resume image can be checked, the next step depends on the > result of checking. > > > is this 'restart point' flexible enough that either the pre-hibernate > > kerenl or the small hibernate kernel could tell the pre-hibernate kernel > > to go into suspend-to-ram mode before doing anything else? > > It is possible for hibernate kernel to pass information back to > pre-hibernate kernel. For example, the information can be passed in jump > buffer page. I think it would be reasonable to have a protocol defined for passing this information, so that it's independent of the kernel version etc. Greetings, Rafael -- "Premature optimization is the root of all evil." - Donald Knuth _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
