On Tue, Jun 10, 2008 at 03:15:06PM +0800, Huang, Ying wrote: > This patch implements devices state save/restore before after kexec. > > > This patch together with features in kexec_jump patch can be used for > following: > > - A simple hibernation implementation without ACPI support. You can > kexec a hibernating kernel, save the memory image of original system > and shutdown the system. When resuming, you restore the memory image > of original system via ordinary kexec load then jump back. > > - Kernel/system debug through making system snapshot. You can make > system snapshot, jump back, do some thing and make another system > snapshot. > > - Cooperative multi-kernel/system. With kexec jump, you can switch > between several kernels/systems quickly without boot process except > the first time. This appears like swap a whole kernel/system out/in. > > - A general method to call program in physical mode (paging turning > off). This can be used to invoke BIOS code under Linux. > > > The following user-space tools can be used with kexec jump: > > - kexec-tools needs to be patched to support kexec jump. The patches > and the precompiled kexec can be download from the following URL: > source: http://khibernation.sourceforge.net/download/release_v10/kexec-tools/kexec-tools-src_git_kh10.tar.bz2 > patches: http://khibernation.sourceforge.net/download/release_v10/kexec-tools/kexec-tools-patches_git_kh10.tar.bz2 > binary: http://khibernation.sourceforge.net/download/release_v10/kexec-tools/kexec_git_kh10 > > - makedumpfile with patches are used as memory image saving tool, it > can exclude free pages from original kernel memory image file. The > patches and the precompiled makedumpfile can be download from the > following URL: > source: http://khibernation.sourceforge.net/download/release_v10/makedumpfile/makedumpfile-src_cvs_kh10.tar.bz2 > patches: http://khibernation.sourceforge.net/download/release_v10/makedumpfile/makedumpfile-patches_cvs_kh10.tar.bz2 > binary: http://khibernation.sourceforge.net/download/release_v10/makedumpfile/makedumpfile_cvs_kh10 > > - An initramfs image can be used as the root file system of kexeced > kernel. An initramfs image built with "BuildRoot" can be downloaded > from the following URL: > initramfs image: http://khibernation.sourceforge.net/download/release_v10/initramfs/rootfs_cvs_kh10.gz > All user space tools above are included in the initramfs image. > > > Usage example of simple hibernation: > > 1. Compile and install patched kernel with following options selected: > > CONFIG_X86_32=y > CONFIG_RELOCATABLE=y > CONFIG_KEXEC=y > CONFIG_CRASH_DUMP=y > CONFIG_PM=y > > 2. Build an initramfs image contains kexec-tool and makedumpfile, or > download the pre-built initramfs image, called rootfs.gz in > following text. > > 3. Prepare a partition to save memory image of original kernel, called > hibernating partition in following text. > > 4. Boot kernel compiled in step 1 (kernel A). > > 5. In the kernel A, load kernel compiled in step 1 (kernel B) with > /sbin/kexec. The shell command line can be as follow: > > /sbin/kexec --load-preserve-context /boot/bzImage --mem-min=0x100000 > --mem-max=0xffffff --initrd=rootfs.gz > > 6. Boot the kernel B with following shell command line: > > /sbin/kexec -e > > 7. The kernel B will boot as normal kexec. In kernel B the memory > image of kernel A can be saved into hibernating partition as > follow: > > jump_back_entry=`cat /proc/cmdline | tr ' ' '\n' | grep kexec_jump_back_entry | cut -d '='` > echo $jump_back_entry > kexec_jump_back_entry > cp /proc/vmcore dump.elf > > Then you can shutdown the machine as normal. > > 8. Boot kernel compiled in step 1 (kernel C). Use the rootfs.gz as > root file system. > One of the concerns raised by hibernation people in the past was to use single boot loader entry to boot normally as well while resuming a kernel. So in this case a user either needs to maintain two boot-loader entries or modify it on the fly. I wished there was a better way to handle that. I am more interested in ability to have multiple kernel loaded in RAM and capability to switch between them. Allows me to take non-disruptive core dumps and somebody wanted to snapshots the kernels. That should still work. [..] > --- a/arch/x86/kernel/machine_kexec_32.c > +++ b/arch/x86/kernel/machine_kexec_32.c > @@ -125,6 +125,12 @@ void machine_kexec(struct kimage *image) > /* Interrupts aren't acceptable while we reboot */ > local_irq_disable(); > > + if (image->preserve_context) { > +#ifdef CONFIG_X86_IO_APIC > + disable_IO_APIC(); > +#endif I think it would be a good idea to put some kind of comment here. We need to put APICs in legacy mode so that we can get timer interrupts in second kernel. kexec/kdump paths already have calls to disable_IO_APIC() in one form or other. kexec jump path also needs one. Thanks Vivek _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
