lkml.org 
[lkml]   [2017]   [Jun]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v1 0/4] coresight: support panic dump functionality
    On Mon, Jun 05, 2017 at 09:57:39AM +0100, Suzuki K Poulose wrote:
    > On 03/06/17 15:42, Leo Yan wrote:
    > >### Introduction ###
    > >
    > >Embedded Trace Buffer (ETB) provides on-chip storage of trace data,
    > >usually has buffer size from 2KB to 8KB. These data has been used for
    > >profiling and this has been well implemented in coresight driver.
    > >
    > >This patch set is to explore ETB RAM data for postmortem debugging.
    > >We could consider ETB RAM data is quite useful for postmortem debugging,
    > >especially if the hardware design with local ETB buffer (ARM DDI 0461B)
    > >chapter 1.2.7. 'Local ETF', with this kind design every CPU has one
    > >dedicated ETB RAM. So it's quite handy that we can use alive CPU to help
    > >dump the hang CPU ETB RAM. Then we can quickly get to know what's the
    > >exact execution flow before its hang.
    > >
    > >Due ETB RAM buffer has small size, if all CPUs shared one ETB buffer
    > >then the trace data for causing error is easily to be overwritten by
    > >other PEs; but even so sometimes we still have chance to go through the
    > >trace data to assist debugging panic issues.
    > >
    > >### Implementation ###
    > >
    > >Firstly we need provide a unified APIs for panic dump functionality, so
    > >it can be easily extended to enable panic dump for multiple drivers. This
    > >is finished by patch 0001, it registers panic notifier, and provide the
    > >general APIs {coresight_add_panic_cb|coresight_del_panic_cb} as helper
    > >functions so any coresight device can add into dump list or delete itself
    > >as needed.
    > >
    > >Generally all the panic dump specific stuff are related to the sinks
    > >devices, so this initial version code it only supports sink devices; and
    > >Patch 0002 is to add and remove panic callback for sink devices.
    > >
    > >Patch 0003 and 0004 are to add panic callback functions for tmc and etb10
    > >drivers; so these two drivers can save specific trace data when panic
    > >happens.
    > >
    > >NOTE: patch 0003 for tmc driver panic callback which has been verified on
    > >Hikey board. patch 0004 for etb10 has not been tested due lack hardware
    > >in hand.
    > >
    >
    > >- After kernel panic happens, the kdump launches dump-capture kernel;
    > > so we need save kernel's dump file on target:
    > > cp /proc/vmcore ./vmcore
    >
    >
    > > After we download vmcore file from Hikey board to host PC, we can
    > > use 'crash' tool to check coresight dump info and extract trace data:
    > > crash vmlinux vmcore
    > > crash> log
    > > [ 37.559337] coresight f6402000.etf: invoke panic dump...
    > > [ 37.565460] coresight-tmc f6402000.etf: Dump ETB buffer 0x2000@0xffff80003b8da180
    > > crash> rd 0xffff80003b8da180 0x2000 -r cs_etb_trace.bin
    > >
    >
    > Have you explored appending the above information as a vmcoreinfo parameter via
    > vmcoreinfo_append_str() ? That would make it easier to list all the information
    > above and if needed, we may be able to extend the makedumpfile to dump the ETB
    > dumps from a given vmcore.

    Thanks for good suggestion, Suzuki. After you pointed out
    vmcoreinfo_append_str() I look at it a bit just now, will add it in
    next version and verify on Hikey.

    Thanks,
    Leo Yan

    \
     
     \ /
      Last update: 2017-06-05 11:38    [W:4.430 / U:0.428 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site