Messages in this thread | | | Date | Mon, 5 Jun 2017 17:27:59 +0800 | From | Leo Yan <> | Subject | Re: [PATCH v1 0/4] coresight: support panic dump functionality |
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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
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