Huang, Ying wrote: > > Kexec jump - The first step to kexec base hibernation
Thanks a lot! > Kexec base hibernation has some potential advantages over uswsusp and > suspend2. Some most obvious advantages are: > > 1. The hibernation image size can exceed half of memory size easily. > 2. The hibernation image can be written to and read from almost > anywhere, such as USB disk, NFS. > > 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 Great! > 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. Sounds easy. > The kernel B is 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 next version. That is, instead of reserving memory > region previously, the needed memory region is backuped before kexec > and restored after jumping back. Actually, backing up from within the normal kernel may produce inter-dependency deadlocks. It's much better to just force-free some memory chunk out to swap. > 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 hibernation method of the devices as proposed earlier in the LKML. > > The kexec jump is implemented in the framework of software suspend. In > fact, the kexec based hibernation can be seen as just implementing the > image writing and reading method of software suspend with a kexeced > Linux 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_SOFTWARE_SUSPEND=y > CONFIG_KEXEC_HIBERNATION=y What about CONFIG_CRASH_DUMP=y ? Also CONFIG_PHYSICAL_START=1000000 (=16M instead of default 1M). > 2. Compile the kexec-tools with kdump and kjump patches added, 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 compiled kernel, 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. Ok, booted with [EMAIL PROTECTED] > 4. Switch hibernation image operations, through shell command as follow: > > echo kexec > /sys/power/hibernation_image_ops Ok. > 5. Boot the kexeced kernel as a crashdump kernel, the same kernel 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` You mean like: # kexec -p vmlinux --args-linux --append="root=/dev/sda1 kexec_jump_buf_pfn = `cat /sys/kernel/kexec_jump_buf_pfn`" # cat c > /proc/sysrq This loads ok. > 6. In the kexec booted kernel, switch hibernation image operations, as > in 4. Ok. > 7. In the kexec booted kernel, trigger the jumping back with following > shell command. > > echo <a>:<b> > /sys/power/resume > > Where <a> and <b> is non-negative integer, at least one of them must > be non-zero. This doesn't switch it, but rather reboots my machine. Thanks! -- Al - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
