> Usage: > > 1. Compile kernel with following options selected: > > CONFIG_X86_32=y > CONFIG_RELOCATABLE=y # not needed strictly, but it is more convenient with it > CONFIG_KEXEC=y > CONFIG_CRASH_DUMP=y # only needed by kexeced kernel to save/restore memory image > CONFIG_PM=y > CONFIG_KEXEC_JUMP=y > > 2. Download the kexec-tools-testing git tree, apply the kexec-tools > kjump patches (or download the source tar ball directly) and > compile. > > 3. Download and compile the krestore tool. > > 4. Prepare 2 root partition used by kernel A and kernel B/C, referred > as /dev/hda, /dev/hdb in following text. This is not strictly > necessary, I use this scheme for testing during development. > > 5. Boot kernel compiled for normal usage (kernal A). > > 6. Load kernel compiled for hibernating/restore usage (kernel B) with > kexec, the same kernel as that of 5 can be used if > CONFIG_RELOCATABLE=y and CONFIG_CRASH_DUMP=y are selected. > > The --elf64-core-headers should be specified in command line of > kexec, because only the 64bit ELF is supported by krestore tool. > > For example, the shell command line can be as follow: > > kexec -p -n /boot/bzImage --mem-min=0x100000 --mem-max=0xffffff > --elf64-core-headers --append="root=/dev/hdb single" > > 7. Jump to the hibernating kernel (kernel B) with following shell > command line: > > kexec -j > > 8. In the hibernating kernel (kernel B), the memory image of > hibernated kernel (kernel A) can be saved as follow: > > cp /proc/vmcore . > cp /sys/kernel/kexec_jump_back_entry . > Here we save also kernel B's pages. > 9. Shutdown or reboot in hibernating kernel (kernel B). > > 10. Boot kernel (kernel C) compiled for hibernating/restore usage on > the root file system /dev/hdb in memory range of kernel B. > > For example, the following kernel command line parameters can be > used: > > root=/dev/hdb single memmap=exactmap memmap=640K at 0K memmap=15M at 1M > 0-640K from kernel A overrides 0-640K of kernel C at restore time. > 11. In restore kernel (kernel C), the memory image of kernel A can be > restored as follow: > > cp kexec_jump_back_entry /sys/kernel/kexec_jump_back_entry > krestore vmcore > > This steps replaces kernel C's pages with kernel B's (at least 15m-16m), saved at step 8, so these kernels should be equal? Or they must be physically located in non-overlapping regions such that C is in B's memory range but non-overlapping. The proposed setup doesn't guaratee this afaics. > 12. Jump back to hibernated kernel (kernel A) > > kexec -b > > Best Regards, > Huang Ying > _______________________________________________ > linux-pm mailing list > linux-pm at lists.linux-foundation.org > https://lists.linux-foundation.org/mailman/listinfo/linux-pm > > --Mika
