On Tue, Feb 13, 2018 at 3:36 PM, Gioh Kim <gurugio@xxxxxxxxx> wrote: > On Tue, Feb 13, 2018 at 11:06 AM, Gioh Kim <gurugio@xxxxxxxxx> wrote: >> On Mon, Feb 12, 2018 at 7:56 AM, Bhupesh SHARMA <bhupesh.linux@xxxxxxxxx> wrote: >>> Hello, >>> >>> On Fri, Feb 9, 2018 at 7:24 PM, Gioh Kim <gurugio@xxxxxxxxx> wrote: >>>> Hello, >>>> >>>> "echo c > /proc/sysrq-trigger" generates the kernel dump but it >>>> reboots the system. >>>> I'd like to generate kernel dump without system reboot. >>>> >>>> I think it is possible to jump to the kdump kernel and generate kernel >>>> dump, and come back to the operating kernel with kexec. >>>> I know I can jump to the kdump kernel with "kexec -e" but I cannot >>>> figure out how to come back to the operating kernel. >>>> >>>> For example, I tried following sequences after reading kexec manual page. >>>> >>>> 0. rebuild kernel with CONFIG_KEXEC_JUMP option >>>> 1. kexec --load=/boot/vmlinuz --initrd=/boot/initrd --reuse-cmdline >>> >>> Instead you should be using something like: >>> # kexec -l /boot/vmlinuz-`uname -r` --initrd=/boot/initramfs-`uname >>> -r`.img --reuse-cmdline --load-preserve-context --mem-min=addr >>> --mem-max=addr >> >> Hello Bhupesh, > > I'm sorry to bother you. > I failed because I booted up wrong kernel without KEXEC_JUMP. > I can jump to kdump kernel with booting a kernel with KEXEC_JUMP. > And I can see "kexec_jump_back_entry=0x00000000000810d2" at kernel > booting parameter. > Now I can jump to kdump kernel and jump back to the original kernel. > > Can I ask just one more question? > After jumping to kdump kernel, there is not /proc/vmcore file. > I checked the kernel enabled CONFIG_PROC_VMCORE option. > What kernel option should I enable to use /proc/vmcore? > Or should I use another file instead /proc/vmcore? > > I'm sorry but please let me ask one more question. I ran "kexec -e" command on kdump kernel, then it just rebooted the system. I guess jumping to the original kernel means resuming the original kernel as it was running. Did I misunderstand? Or my machine did not work correctly? -- Best regards, Gioh Kim _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
