Hello,
I'm confused about early consoles and earlyprintk, and all that good stuff.
When my kernel panics, I don't get the expected output.
Using "mem=256M ignore_loglevel earlyprintk"
Uncompressing Linux... done, booting the kernel.
[ 0.000000] Booting Linux on physical CPU 0x0
[ 0.000000] Linux version 4.9.7-1-rc2 (gcc version 5.3.1 20160113 (Linaro GCC 5.3-2016.02) ) #153 SMP PREEMPT Fri Mar 3 17:31:37 CET 2017
[ 0.000000] CPU: ARMv7 Processor [413fc090] revision 0 (ARMv7), cr=10c5387d
[ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[ 0.000000] OF: fdt:Machine model: Sigma Designs SMP8758 Vantage-1172 Rev E1
[ 0.000000] debug: ignoring loglevel setting.
[ 0.000000] bootconsole [earlycon0] enabled
[ 0.000000] Memory policy: Data cache writealloc
[ 0.000000] On node 0 totalpages: 65536
[ 0.000000] free_area_init_node: node 0, pgdat c10234c0, node_mem_map cfdf9000
[ 0.000000] Normal zone: 512 pages used for memmap
[ 0.000000] Normal zone: 0 pages reserved
[ 0.000000] Normal zone: 65536 pages, LIFO batch:15
[ 0.000000] percpu: Embedded 14 pages/cpu @cfdd7000 s24960 r8192 d24192 u57344
[ 0.000000] pcpu-alloc: s24960 r8192 d24192 u57344 alloc=14*4096
[ 0.000000] pcpu-alloc: [0] 0 [0] 1
[ 0.000000] Built 1 zonelists in Zone order, mobility grouping on. Total pages: 65024
[ 0.000000] Kernel command line: mem=256M ignore_loglevel earlyprintk
[ 0.000000] PID hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.000000] Dentry cache hash table entries: 32768 (order: 5, 131072 bytes)
[ 0.000000] Inode-cache hash table entries: 16384 (order: 4, 65536 bytes)
[ 0.000000] Memory: 243980K/262144K available (4096K kernel code, 146K rwdata, 876K rodata, 10240K init, 233K bss, 18164K reserved, 0K cma-reserved, 0K highmem)
[ 0.000000] Virtual kernel memory layout:
[ 0.000000] vector : 0xffff0000 - 0xffff1000 ( 4 kB)
[ 0.000000] fixmap : 0xffc00000 - 0xfff00000 (3072 kB)
[ 0.000000] vmalloc : 0xd0800000 - 0xff800000 ( 752 MB)
[ 0.000000] lowmem : 0xc0000000 - 0xd0000000 ( 256 MB)
[ 0.000000] pkmap : 0xbfe00000 - 0xc0000000 ( 2 MB)
[ 0.000000] modules : 0xbf000000 - 0xbfe00000 ( 14 MB)
[ 0.000000] .text : 0xc0008000 - 0xc0500000 (5088 kB)
[ 0.000000] .init : 0xc0600000 - 0xc1000000 (10240 kB)
[ 0.000000] .data : 0xc1000000 - 0xc1024860 ( 147 kB)
[ 0.000000] .bss : 0xc1024860 - 0xc105ed40 ( 234 kB)
[ 0.000000] Preemptible hierarchical RCU implementation.
[ 0.000000] Build-time adjustment of leaf fanout to 32.
[ 0.000000] RCU restricting CPUs from NR_CPUS=4 to nr_cpu_ids=2.
[ 0.000000] RCU: Adjusting geometry for rcu_fanout_leaf=32, nr_cpu_ids=2
[ 0.000000] NR_IRQS:16 nr_irqs:16 16
[ 0.000000] L2C-310 enabling early BRESP for Cortex-A9
[ 0.000000] L2C-310 ID prefetch enabled, offset 4 lines
[ 0.000000] L2C-310 dynamic clock gating enabled, standby mode enabled
[ 0.000000] L2C-310 cache controller enabled, 8 ways, 512 kB
[ 0.000000] L2C-310: CACHE_ID 0x410000c8, AUX_CTRL 0x72860401
[ 0.000000] clocksource: tango-xtal: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 70787423951 ns
[ 0.000004] sched_clock: 32 bits at 27MHz, resolution 37ns, wraps every 79536431085ns
[ 0.007960] Switching to timer-based delay loop, resolution 37ns
[ 0.014325] Console: colour dummy device 80x30
[ 0.018885] console [tty0] enabled
[ 0.022396] bootconsole [earlycon0] disabled
And it hangs there.
If I use an explicit console= configuration, I do see the panic.
Using "mem=256M ignore_loglevel console=ttyS0,115200 earlyprintk"
Uncompressing Linux... done, booting the kernel.
[ 0.000000] Booting Linux on physical CPU 0x0
[ 0.000000] Linux version 4.9.7-1-rc2 (gcc version 5.3.1 20160113 (Linaro GCC 5.3-2016.02) ) #153 SMP PREEMPT Fri Mar 3 17:31:37 CET 2017
[ 0.000000] CPU: ARMv7 Processor [413fc090] revision 0 (ARMv7), cr=10c5387d
[ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[ 0.000000] OF: fdt:Machine model: Sigma Designs SMP8758 Vantage-1172 Rev E1
[ 0.000000] debug: ignoring loglevel setting.
[ 0.000000] bootconsole [earlycon0] enabled
[ 0.000000] Memory policy: Data cache writealloc
[ 0.000000] On node 0 totalpages: 65536
[ 0.000000] free_area_init_node: node 0, pgdat c10234c0, node_mem_map cfdf9000
[ 0.000000] Normal zone: 512 pages used for memmap
[ 0.000000] Normal zone: 0 pages reserved
[ 0.000000] Normal zone: 65536 pages, LIFO batch:15
[ 0.000000] percpu: Embedded 14 pages/cpu @cfdd7000 s24960 r8192 d24192 u57344
[ 0.000000] pcpu-alloc: s24960 r8192 d24192 u57344 alloc=14*4096
[ 0.000000] pcpu-alloc: [0] 0 [0] 1
[ 0.000000] Built 1 zonelists in Zone order, mobility grouping on. Total pages: 65024
[ 0.000000] Kernel command line: mem=256M ignore_loglevel console=ttyS0,115200 earlyprintk
[ 0.000000] PID hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.000000] Dentry cache hash table entries: 32768 (order: 5, 131072 bytes)
[ 0.000000] Inode-cache hash table entries: 16384 (order: 4, 65536 bytes)
[ 0.000000] Memory: 243980K/262144K available (4096K kernel code, 146K rwdata, 876K rodata, 10240K init, 233K bss, 18164K reserved, 0K cma-reserved, 0K highmem)
[ 0.000000] Virtual kernel memory layout:
[ 0.000000] vector : 0xffff0000 - 0xffff1000 ( 4 kB)
[ 0.000000] fixmap : 0xffc00000 - 0xfff00000 (3072 kB)
[ 0.000000] vmalloc : 0xd0800000 - 0xff800000 ( 752 MB)
[ 0.000000] lowmem : 0xc0000000 - 0xd0000000 ( 256 MB)
[ 0.000000] pkmap : 0xbfe00000 - 0xc0000000 ( 2 MB)
[ 0.000000] modules : 0xbf000000 - 0xbfe00000 ( 14 MB)
[ 0.000000] .text : 0xc0008000 - 0xc0500000 (5088 kB)
[ 0.000000] .init : 0xc0600000 - 0xc1000000 (10240 kB)
[ 0.000000] .data : 0xc1000000 - 0xc1024860 ( 147 kB)
[ 0.000000] .bss : 0xc1024860 - 0xc105ed40 ( 234 kB)
[ 0.000000] Preemptible hierarchical RCU implementation.
[ 0.000000] Build-time adjustment of leaf fanout to 32.
[ 0.000000] RCU restricting CPUs from NR_CPUS=4 to nr_cpu_ids=2.
[ 0.000000] RCU: Adjusting geometry for rcu_fanout_leaf=32, nr_cpu_ids=2
[ 0.000000] NR_IRQS:16 nr_irqs:16 16
[ 0.000000] L2C-310 enabling early BRESP for Cortex-A9
[ 0.000000] L2C-310 ID prefetch enabled, offset 4 lines
[ 0.000000] L2C-310 dynamic clock gating enabled, standby mode enabled
[ 0.000000] L2C-310 cache controller enabled, 8 ways, 512 kB
[ 0.000000] L2C-310: CACHE_ID 0x410000c8, AUX_CTRL 0x72860401
[ 0.000000] clocksource: tango-xtal: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 70787423951 ns
[ 0.000004] sched_clock: 32 bits at 27MHz, resolution 37ns, wraps every 79536431085ns
[ 0.007961] Switching to timer-based delay loop, resolution 37ns
[ 0.014325] Console: colour dummy device 80x30
[ 0.018899] Calibrating delay loop (skipped), value calculated using timer frequency.. 54.25 BogoMIPS (lpj=90000)
[ 0.029316] pid_max: default: 32768 minimum: 301
[ 0.034135] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.040876] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.048527] CPU: Testing write buffer coherency: ok
[ 0.053736] CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
[ 0.059560] Setting up static identity map for 0x80100000 - 0x80100034
[ 0.120467] CPU1: thread -1, cpu 1, socket 0, mpidr 80000001
[ 0.120530] Brought up 2 CPUs
[ 0.129381] SMP: Total of 2 processors activated (108.50 BogoMIPS).
[ 0.135771] CPU: All CPU(s) started in SVC mode.
[ 0.141062] devtmpfs: initialized
[ 0.145393] VFP support v0.3: implementor 41 architecture 3 part 30 variant 9 rev 4
[ 0.153490] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 6370867519511994 ns
[ 0.163772] NET: Registered protocol family 16
[ 0.169026] DMA: preallocated 256 KiB pool for atomic coherent allocations
[ 0.177030] Kernel panic - not syncing: FAKE PANIC
[ 0.177030]
[ 0.183510] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.9.7-1-rc2 #153
[ 0.190154] Hardware name: Sigma Tango DT
[ 0.194301] [<c010ed94>] (unwind_backtrace) from [<c010ae24>] (show_stack+0x10/0x14)
[ 0.202176] [<c010ae24>] (show_stack) from [<c02cecc0>] (dump_stack+0x78/0x8c)
[ 0.209527] [<c02cecc0>] (dump_stack) from [<c018b634>] (panic+0xdc/0x248)
[ 0.216530] [<c018b634>] (panic) from [<c0607acc>] (xenv_lookup.constprop.1+0x0/0x64)
[ 0.224493] [<c0607acc>] (xenv_lookup.constprop.1) from [<c0220830>] (proc_create_data+0x74/0xb8)
[ 0.233501] [<c0220830>] (proc_create_data) from [<c050fa08>] (0xc050fa08)
[ 0.240499] CPU1: stopping
[ 0.243303] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.9.7-1-rc2 #153
[ 0.249946] Hardware name: Sigma Tango DT
[ 0.254065] [<c010ed94>] (unwind_backtrace) from [<c010ae24>] (show_stack+0x10/0x14)
[ 0.261937] [<c010ae24>] (show_stack) from [<c02cecc0>] (dump_stack+0x78/0x8c)
[ 0.269283] [<c02cecc0>] (dump_stack) from [<c010dc10>] (handle_IPI+0x198/0x1ac)
[ 0.276803] [<c010dc10>] (handle_IPI) from [<c01014a4>] (gic_handle_irq+0x88/0x8c)
[ 0.284499] [<c01014a4>] (gic_handle_irq) from [<c010b90c>] (__irq_svc+0x6c/0xa8)
[ 0.292104] Exception stack(0xcf859f98 to 0xcf859fe0)
[ 0.297263] 9f80: 00000001 00000000
[ 0.305568] 9fa0: 000002d8 c0114620 cf858000 c1002fe4 c1003048 00000002 c100ba2e 413fc090
[ 0.313874] 9fc0: 00000000 00000000 32dcd555 cf859fe8 c0108220 c0108224 60000013 ffffffff
[ 0.322182] [<c010b90c>] (__irq_svc) from [<c0108224>] (arch_cpu_idle+0x38/0x3c)
[ 0.329707] [<c0108224>] (arch_cpu_idle) from [<c0151f4c>] (cpu_startup_entry+0xcc/0x144)
[ 0.338015] [<c0151f4c>] (cpu_startup_entry) from [<8010154c>] (0x8010154c)
[ 0.345103] ---[ end Kernel panic - not syncing: FAKE PANIC
I suppose this is related to my DT description?
chosen {
stdout-path = "serial:115200n8";
};
Isn't stdout-path = "serial:115200n8" supposed to be equivalent to
console=ttyS0,115200 ?
I must be missing something.
Regards.
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