On Friday, 28 September 2007 11:03, Huang, Ying wrote: > In following text, khibernation is the abbreviation of "kexec based > hibernation". > > > 1. Kexec/kdump and ACPI > > With Linux kernel 2.6.23-rc6-mm1 + khibernation patches on my IBM T42, > khibernation works well with ACPI. That is, the following is possible > with ACPI enabled. > > a. Boot kernel A with ACPI on > b. Put devices in quiescent and low power state How exactly? > c. Kexec a new kernel B with ACPI on > d. Jump back to kernel A > > I think it should be a standard feature that the kexeced kernel can be > booted properly with devices been put in low power state. Agreed. > Because, if the dynamic power management is enabled, some idle devices will > be put into low power state even in G0, when a crash dump is triggered, the > crash dump kernel should be booted properly even with devices been put > in low power state. If this not supported, the crash dump can not work > on system with dynamic power management on. > > > 2. Khibernation and ACPI > > Khibernation can work with ACPI even without feature above, because > image-writing kernel with initramfs can be booted independent of > device state. The scheme is as follow: > > a. Boot kernel A with ACPI on > b. Put all devices in quiescent and low power state > c. Execute _PTS of ACPI > d. Kexec a new kernel B with ACPI on. This may execute ACPI methods that should not be called after _PTS. Unless you tell the new kernel not to initialize ACPI, that is. > The root filesystem is initramfs, so that, the only devices needed by kernel > B is timer. > e. In kernel B, put needed devices back to normal state. > f. Write memory image of kernel A out > g. Put all devices in quiescent and low power state > h. Execute acpi_enter_sleep_state(ACPI_STATE_S4) Yes, apart from d. this looks doable. Greetings, Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
