On Sunday, 15 July 2007 09:13, Huang, Ying wrote: > The changelog between v1 and v2 > > 1. The kexec jump implementation is put into the kexec/kdump > framework instead of software suspend framework. The device > and CPU state save/restore code of software suspend is called > when needed. > > 2. The same code path is used for both kexec a new kernel and jump > back to original kernel. > > The complete changelog of the patch is as follow: > > --- > > Kexec base hibernation has some potential advantages over uswsusp and > TuxOnIce (suspend2). Some most obvious advantages are: > > 1. The hibernation image size can exceed half of memory size easily. In TuxOnIce (suspend2) there's no such limitation. > 2. The hibernation image can be written to and read from almost > anywhere, such as USB disk, NFS. You can do this, too, with uswsusp. > This patch implements the functionality of "jumping from kexeced > kernel to original kernel". That is, the following sequence is > possible: > > 1. Boot a kernel A > 2. Work under kernel A > 3. Kexec another kernel B in kernel A > 4. Work under kernel B > 5. Jump from kernel B to kernel A > 6. Continue work under kernel A > > This is the first step to implement kexec based hibernation. If the > memory image of kernel A is written to or read from a permanent media > in step 4, a preliminary version of kexec based hibernation can be > implemented. > > The kernel B run as a crashdump kernel in reserved memory region. This > is the biggest constrains of the patch. It is planed to be eliminated > in the future version. That is, instead of reserving memory region > previously, the needed memory region is backupped before kexec and > restored after jumping back. > > Another constrains of the patch is that the CONFIG_ACPI must be turned > off to make kexec jump work. Because ACPI will put devices into low > power state, the kexeced kernel can not be booted properly under > it. This constrains can be eliminated by separating the suspend method > and hibernate method of the devices as proposed earlier in the LKML. > > The kexec jump is implemented in the framework of kexec/kdump. In > sys_reboot, a new command named LINUX_REBOOT_CMD_KJUMP is defined to > trigger the jumping to (executing) the new kernel or jump back to the > original kernel. > > Now, only the i386 architecture is supported. The patch is based on > Linux kernel 2.6.22, and has been tested on my IBM T42. > > 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_PM=y > CONFIG_KEXEC_JUMP=y > > 2. Compile the kexec-tools with kdump and kjump patches, the > kdump patch can be found at: > > http://lse.sourceforge.net/kdump/patches/kexec-tools-1.101-kdump10.patch > > While, the kexec-tools kjump patch is appended with the mail. > > 3. Boot kernel compiled for normal usage, the reserved crash kernel > memory region must be added to kernel command line as following: > > crashkernel=<XX>M@<XX>M > > Where, <XX> should be replaced by the real memory size and position. > > 4. Load kernel compiled for hibernating usage as a crashdump kernel > with kexec, the same kernel as that of 3 can be used if > CONFIG_RELOCATABLE=y is selected. The kernel command line option as > following must be appended to kernel command line. > > kexec_jump_buf_pfn=`cat /sys/kernel/kexec_jump_buf_pfn` > > For example, the shell command line can be as follow: > > kexec -p /boot/vmlinux --args-linux --append="root=/dev/hdb signal > kexec_jump_buf_pfn=`cat /sys/kernel/kexec_jump_buf_pfn`" > > 5. Boot the hibernating kernel with following shell command line: > > kexec -j > > 6. In the kexec booted kernel, trigger the jumping back with following > shell command. > > kexec -j Well, I think that's _way_ too much complicated to be useful for hibernation on systems that are set up and administered by average users. 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
