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| author | Anton Vorontsov <anton.vorontsov@linaro.org> | 2012-07-09 17:10:44 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-07-17 10:14:17 -0700 |
| commit | a694d1b5916a486ce25fb5f2b39f2627f7afd5f3 (patch) | |
| tree | 541a95c58880019cffe90c79a9468746893caa0d /Documentation/ramoops.txt | |
| parent | c2b7113261c5bb49031a15b833e59ea2d8ec4074 (diff) | |
| download | lwn-a694d1b5916a486ce25fb5f2b39f2627f7afd5f3.tar.gz lwn-a694d1b5916a486ce25fb5f2b39f2627f7afd5f3.zip | |
pstore/ram: Add ftrace messages handling
The ftrace log size is configurable via ramoops.ftrace_size
module option, and the log itself is available via
<pstore-mount>/ftrace-ramoops file.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/ramoops.txt')
| -rw-r--r-- | Documentation/ramoops.txt | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/Documentation/ramoops.txt b/Documentation/ramoops.txt index 59a74a8ee2e5..197ad59ab9bf 100644 --- a/Documentation/ramoops.txt +++ b/Documentation/ramoops.txt @@ -94,3 +94,28 @@ timestamp and a new line. The dump then continues with the actual data. The dump data can be read from the pstore filesystem. The format for these files is "dmesg-ramoops-N", where N is the record number in memory. To delete a stored record from RAM, simply unlink the respective pstore file. + +5. Persistent function tracing + +Persistent function tracing might be useful for debugging software or hardware +related hangs. The functions call chain log is stored in a "ftrace-ramoops" +file. Here is an example of usage: + + # mount -t debugfs debugfs /sys/kernel/debug/ + # cd /sys/kernel/debug/tracing + # echo function > current_tracer + # echo 1 > options/func_pstore + # reboot -f + [...] + # mount -t pstore pstore /mnt/ + # tail /mnt/ftrace-ramoops + 0 ffffffff8101ea64 ffffffff8101bcda native_apic_mem_read <- disconnect_bsp_APIC+0x6a/0xc0 + 0 ffffffff8101ea44 ffffffff8101bcf6 native_apic_mem_write <- disconnect_bsp_APIC+0x86/0xc0 + 0 ffffffff81020084 ffffffff8101a4b5 hpet_disable <- native_machine_shutdown+0x75/0x90 + 0 ffffffff81005f94 ffffffff8101a4bb iommu_shutdown_noop <- native_machine_shutdown+0x7b/0x90 + 0 ffffffff8101a6a1 ffffffff8101a437 native_machine_emergency_restart <- native_machine_restart+0x37/0x40 + 0 ffffffff811f9876 ffffffff8101a73a acpi_reboot <- native_machine_emergency_restart+0xaa/0x1e0 + 0 ffffffff8101a514 ffffffff8101a772 mach_reboot_fixups <- native_machine_emergency_restart+0xe2/0x1e0 + 0 ffffffff811d9c54 ffffffff8101a7a0 __const_udelay <- native_machine_emergency_restart+0x110/0x1e0 + 0 ffffffff811d9c34 ffffffff811d9c80 __delay <- __const_udelay+0x30/0x40 + 0 ffffffff811d9d14 ffffffff811d9c3f delay_tsc <- __delay+0xf/0x20 |