Hello Folks, I have reserved about 150MB of crash kernel space and was trying to test loading the crash kernel using kexec. As it so happens, crash kernel never boots. I tried using zImage, uImage or vmlinux as well. After the message "Bye", nothing happens and the u-boot for the main kernel takes over after some time(10 seconds or so), loading the main kernel image again. How can I debug this further? Any pointers will help. regards Mahesh Kernel version: 3.4.0, arch = ARM. Image size is : 13450816 bytes cat /proc/iomem ... ... 37a00000-37bfffff : registers 41500000-445fffff : System RAM 41508000-41cd2acb : Kernel code 42708000-428db69b : Kernel data 44800000-5fbfffff : System RAM 44800000-4ddfffff : Crash kernel # kexec -t zImage -d -p crash_kernel_zImage --command-line="console=ttymxc2,115200 init=/init rw rootfstype=ext4 rootwait" --atags --mem-min=0x44800000 kexec_flags == 1 kernel: 0x364008 kernel_size: 0xcd0390 MEMORY RANGES 0000000041500000-00000000445fffff (0) 0000000044800000-000000005fbfffff (0) zImage header: 0x016f2818 0x00000000 0x00cd0390 zImage size 0xcd0390, file size 0xcd0390 Reserved memory ranges 0000000044800000-000000004ddfffff (0) Coredump memory ranges 0000000041500000-00000000445fffff (0) 000000004de00000-000000005fbfffff (0) kernel symbol _stext vaddr = 0xc0008180 phys offset = 0x41500000, page offset = c0000000 Crash kernel memory [0x44800000-0x4ddfffff] Using 32-bit ELF core format get_crash_notes_per_cpu: crash_notes addr = 5f5c80b4, size = 1024 Elf header: p_type = 4, p_offset = 0x5f5c80b4 p_paddr = 0x5f5c80b4 p_vaddr = 0x0 p_filesz = 0x400 p_memsz = 0x400 get_crash_notes_per_cpu: crash_notes addr = 5f5c70b4, size = 1024 Elf header: p_type = 4, p_offset = 0x5f5c70b4 p_paddr = 0x5f5c70b4 p_vaddr = 0x0 p_filesz = 0x400 p_memsz = 0x400 vmcoreinfo header: p_type = 4, p_offset = 0x428a2a6c p_paddr = 0x428a2a6c p_vaddr = 0x0 p_filesz = 0x1000 p_memsz = 0x1000 Elf header: p_type = 1, p_offset = 0x41500000 p_paddr = 0x41500000 p_vaddr = 0xc0000000 p_filesz = 0x3100000 p_memsz = 0x3100000 Elf header: p_type = 1, p_offset = 0x4de00000 p_paddr = 0x4de00000 p_vaddr = 0xcc900000 p_filesz = 0x11e00000 p_memsz = 0x11e00000 elfcorehdr: 0x4dd00000 crashkernel: [0x44800000 - 0x4ddfffff] (150M) memory range: [0x41500000 - 0x445fffff] (49M) memory range: [0x4de00000 - 0x5fbfffff] (286M) base 1149239296l, start 1149239296 end 1306525695 kexec_load: entry = 0x44808000 flags = 0x280001 nr_segments = 3 segment[0].buf = 0x1034c00 segment[0].bufsz = 0x14c segment[0].mem = 0x44801000 segment[0].memsz = 0x1000 segment[1].buf = 0x364008 segment[1].bufsz = 0xcd0390 segment[1].mem = 0x44808000 segment[1].memsz = 0xcd1000 segment[2].buf = 0x10347a8 segment[2].bufsz = 0x400 segment[2].mem = 0x4dd00000 segment[2].memsz = 0x1000 # # echo c > /proc/sysrq-trigger [17609.062168] SysRq : Trigger a crash [17609.091846] Unable to handle kernel NULL pointer dereference at virtual address 00000000 [17609.188722] pgd = d3c84000 [17609.221025] [00000000] *pgd=55105831, *pte=00000000, *ppte=00000000 [17609.296001] Internal error: Oops: 817 [#1] SMP ARM [17609.353296] Modules linked in: ath_pktlog(PO) umac(O) ath_dev(PO) ath_spectral(PO) ath_dfs(PO) ath_rate_atheros(PO) ath_hal(PO) asf(PO) adf(PO) asap_mod(PO) drvlog_mod(PO) bonding qca_nss_crypto(O) qca_nss_drv(O) qca_nss_gmac(O) [last unloaded: crc_ccitt] [17609.624149] CPU: 0 Tainted: P O (3.4.103 #maheshvenkateshwaran at mv_iap43_2-ENG.0000) [17609.730397] PC is at sysrq_handle_crash+0x18/0x20 [17609.786629] LR is at __handle_sysrq+0xac/0x160 [17609.839769] pc : [<c01ded88>] lr : [<c01df274>] psr: 20000093 [17609.839769] sp : d3c97f18 ip : fa001028 fp : 00000038 [17609.977257] r10: 00000007 r9 : 00000000 r8 : 00000000 [17610.039769] r7 : 60000013 r6 : c12e72f8 r5 : 00000063 r4 : c12d6128 [17610.117901] r3 : 00000000 r2 : 00000001 r1 : 20000093 r0 : 00000063 [17610.196033] Flags: nzCv IRQs off FIQs on Mode SVC_32 ISA ARM Segment user [17610.282474] Control: 10c5787d Table: 5518406a DAC: 00000015 [17610.351234] [17610.351234] PC: 0xc01ded88: [17610.402281] ed88 e5c32000 e12fff1e e92d4038 e2405030 e3064128 e34c412d e1a01005 e30d0d90 [17610.500187] eda8 e34c0076 e3a03007 e5843000 eb066665 e5845000 e8bd8038 e92d4038 e1a05000 [17610.598094] [17610.598094] LR: 0xc01df274: [17610.649141] f274 ea000019 e59f0094 e3a05000 eb066532 e59f608c e5b63004 e3530000 1a000002 [17610.747079] f294 ea00000b e2811001 ea000001 e59f2070 e3a01000 e5b20004 e1530000 1afffff8 [17610.844986] [17610.844986] SP: 0xd3c97f18: [17610.896033] 7f18 d3c90000 00000002 c01df328 d9955240 402e86e4 00000002 d3c97f80 c01df360 [17610.993939] 7f38 de184080 c0120b04 d3c97f80 d9955240 00000002 402e86e4 d3c97f80 00000000 [17611.091846] [17611.091846] IP: 0xfa001028: [17611.142893] 1028 a09eb01d 00000001 00000000 00000003 00000000 00000000 00000000 0006b3f0 [17611.240831] 1048 00000c7c 00190000 00000000 00000000 14ed482b 00230000 00000000 00000000 [17611.338738] [17611.338738] R4: 0xc12d6128: [17611.389784] 6128 00000007 00000004 00000001 00000007 00000000 0afa0afa dead4ead ffffffff [17611.487691] 6148 ffffffff 00170017 dead4ead ffffffff ffffffff d9647f78 d9647f78 00000004 [17611.585598] [17611.585630] R6: 0xc12e72f8: [17611.636645] 72f8 c01ded70 c076defc c076df04 00000008 c01df088 c076df14 c076df2c 00000040 [17611.734583] 7318 c01def70 c076df40 c076df58 00000040 c01df068 c076df70 c076df84 00000040 [17611.832490] Process busybox (pid: 25437, stack limit = 0xd3c902f0) [17611.906436] Stack: (0xd3c97f18 to 0xd3c98000) [17611.958544] 7f00: d3c90000 00000002 [17612.056451] 7f20: c01df328 d9955240 402e86e4 00000002 d3c97f80 c01df360 de184080 c0120b04 [17612.154358] 7f40: d3c97f80 d9955240 00000002 402e86e4 d3c97f80 00000000 00000000 c00e2cac [17612.252296] 7f60: d5ac2680 d5ac2680 d9955240 402e86e4 00000002 00000004 00000000 c00e2f08 [17612.350203] 7f80: 00000000 00000000 ffffffff 00000000 402e6278 00000002 402e86e4 c000e104 [17612.448110] 7fa0: d3c90000 c000df80 402e6278 00000002 00000001 402e86e4 00000002 402bd2c8 [17612.546048] 7fc0: 402e6278 00000002 402e86e4 00000004 402e6000 00000020 00000100 00000038 [17612.643955] 7fe0: 00000002 befb4ba0 402bc834 402d792c 60000010 00000001 00000000 00000000 [17612.741862] cpu0 [17612.763761] [<c01ded88>] (sysrq_handle_crash+0x18/0x20) from [<c01df274>] (__handle_sysrq+0xac/0x160) [17612.874164] [<c01df274>] (__handle_sysrq+0xac/0x160) from [<c01df360>] (write_sysrq_trigger+0x38/0x48) [17612.985630] [<c01df360>] (write_sysrq_trigger+0x38/0x48) from [<c0120b04>] (proc_reg_write+0x80/0x94) [17613.096064] [<c0120b04>] (proc_reg_write+0x80/0x94) from [<c00e2cac>] (vfs_write+0xb4/0x134) [17613.197095] [<c00e2cac>] (vfs_write+0xb4/0x134) from [<c00e2f08>] (sys_write+0x40/0x6c) [17613.292940] [<c00e2f08>] (sys_write+0x40/0x6c) from [<c000df80>] (ret_fast_syscall+0x0/0x30) [17613.393971] Code: e3a02001 e5832000 f57ff04f e3a03000 (e5c32000) [17613.468479] Loading crashdump kernel... [17613.512715] image->start 44808000 [17613.552296] kexec start address 44808000, [17613.602281] reboot_code_buffer 0xc3300000, [17613.653327] reboot_code_buffer_phys 44800000, [17613.707498] kexec_mach_type 4704 [17613.748141] Bye!