On Fri, Jun 15, 2012 at 10:07:00AM -0700, Anton Vorontsov wrote: > Hi all, > > In v2: > - Do not introduce a separate 'persistent' tracer, but introduce an > option to the existing 'function' tracer. > > Rationale for this patch set: > > With this support kernel can save functions call chain log into a > persistent ram buffer that can be decoded and dumped after reboot > through pstore filesystem. It can be used to determine what function > was last called before a hang or an unexpected reset (caused by, for > example, a buggy driver that abuses HW). > > Here's a "nano howto", to get the idea: > > # 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 > > Mostly the code comes from trace_persistent.c driver found in the > Android git tree, written by Colin Cross <ccross@xxxxxxxxxxx> > (according to sign-off history). I reworked the driver a little bit, > and ported it to pstore subsystem. This looks fine to me, but as it touches pstore and tracing code, I can't apply it without acks from the relevant maintainers/owners. thanks, greg k-h _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
