Re: [PATCH v5 00/17] Add Qualcomm Minidump kernel driver related support

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On Sun, Sep 10, 2023 at 01:46:01AM +0530, Mukesh Ojha wrote:
> Hi All,
> This is to continuation from the conversation happened at v4
> We have put abstract on LPC on this topic as well as initiated a mail thread
> with other SoC vendors but did not get much traction on it.
> We explored most of possiblity present in kernel to address this issue[1] but
> solution like kdump/fadump does not seems safe/secure/performant from our
> perspective.
> Hence, with this series we tried to make the minidump kernel driver, simple
> and tied with pstore frontends, so that it collects the present available
> frontends data like dmesg, ftrace, pmsg, ftrace., Also, we will be working
> towards enhancing generic pstore to capture more debug data which will be
> helpful for first hand of debugging that can benefit both other pstore users
> as well as us as minidump users.
> One of the proposal made here,
> Looking forward for your comments.
> Thanks,
> Mukesh
> [1]
> Minidump is a best effort mechanism to collect useful and predefined data
> for first level of debugging on end user devices running on Qualcomm SoCs.
> It is built on the premise that System on Chip (SoC) or subsystem part of
> SoC crashes, due to a range of hardware and software bugs. Hence, the
> ability to collect accurate data is only a best-effort. The data collected
> could be invalid or corrupted, data collection itself could fail, and so on.
> Qualcomm devices in engineering mode provides a mechanism for generating
> full system ramdumps for post mortem debugging. But in some cases it's
> however not feasible to capture the entire content of RAM. The minidump
> mechanism provides the means for selecting which snippets should be
> included in the ramdump.
> The core of SMEM based minidump feature is part of Qualcomm's boot
> firmware code. It initializes shared memory (SMEM), which is a part of
> DDR and allocates a small section of SMEM to minidump table i.e also
> called global table of content (G-ToC). Each subsystem (APSS, ADSP, ...)
> has their own table of segments to be included in the minidump and all
> get their reference from G-ToC. Each segment/region has some details
> like name, physical address and it's size etc. and it could be anywhere
> scattered in the DDR.
> Existing upstream Qualcomm remoteproc driver[1] already supports SMEM
> based minidump feature for remoteproc instances like ADSP, MODEM, ...
> where predefined selective segments of subsystem region can be dumped
> as part of coredump collection which generates smaller size artifacts
> compared to complete coredump of subsystem on crash.
> [1]
> In addition to managing and querying the APSS minidump description,
> the Linux driver maintains a ELF header in a segment. This segment
> gets updated with section/program header whenever a new entry gets
> registered.
> Changes in v5:
>  - On suggestion from Pavan.k, to have single function call for minidump collection
>    from remoteproc driver, separated the logic to have separate minidump file called
>    qcom_rproc_minidump.c and also renamed the function from qcom_minidump() to 
>    qcom_rproc_minidump(); however, dropped his suggestion about rework on lazy deletion
>    during region unregister in this series, will pursue it in next series.
>  - To simplify the minidump driver, removed the complication for frontend and different
>    backend from Greg suggestion, will pursue this once main driver gets mainlined.
>  - Move the dynamic ramoops region allocation from Device tree approach to command line
>    approch with the introduction command line parsing and memblock reservation during
>    early boot up; Not added documentation about it yet, will add if it gets positive
>    response.
>  - Exporting linux banner from kernel to make minidump build also as module, however,
>    minidump is a debug module and should be kernel built to get most debug information
>    from kernel.
>  - Tried to address comments given on dload patch series. 
> Changes in v4:
>  - Redesigned the driver and divided the driver into front end and backend (smem) so
>    that any new backend can be attached easily to avoid code duplication.
>  - Patch reordering as per the driver and subsystem to easier review of the code.
>  - Removed minidump specific code from remoteproc to minidump smem based driver.
>  - Enabled the all the driver as modules.
>  - Address comments made on documentation and yaml and Device tree file [Krzysztof/Konrad]
>  - Address comments made qcom_pstore_minidump driver and given its Device tree
>    same set of properties as ramoops. [Luca/Kees]
>  - Added patch for MAINTAINER file.
>  - Include defconfig change as one patch as per [Krzysztof] suggestion.
>  - Tried to remove the redundant file scope variables from the module as per [Krzysztof] suggestion.
>  - Addressed comments made on dload mode patch v6 version
> Changes in v3:
>  - Addressed most of the comments by Srini on v2 and refactored the minidump driver.
>     - Added platform device support
>     - Unregister region support.
>  - Added update region for clients.
>  - Added pending region support.
>  - Modified the documentation guide accordingly.
>  - Added qcom_pstore_ramdump client driver which happen to add ramoops platform
>    device and also registers ramoops region with minidump.
>  - Added download mode patch series with this minidump series.
> Changes in v2:
>  - Addressed review comment made by [quic_tsoni/bmasney] to add documentation.
>  - Addressed comments made by [srinivas.kandagatla]
>  - Dropped pstore 6/6 from the last series, till i get conclusion to get pstore
>    region in minidump.
>  - Fixed issue reported by kernel test robot.
> Changes in v1:
> Testing of the patches has been done on sm8450 target after enabling config like
> CONFIG_PSTORE_RAM and CONFIG_PSTORE_CONSOLE and once the device boots up.
>  echo mini > /sys/module/qcom_scm/parameters/download_mode
> Try crashing it via devmem2 0xf11c000(this is known to create xpu violation and
> and put the device in download mode) on command prompt.
> Default storage type is set to via USB, so minidump would be downloaded with the
> help of x86_64 machine (running PCAT tool) attached to Qualcomm device which has
> backed minidump boot firmware support.
> This will make the device go to download mode and collect the minidump on to the
> attached x86 machine running the Qualcomm PCAT tool(This comes as part Qualcomm
> package manager kit).
> After that we will see a bunch of predefined registered region as binary blobs files
> starts with md_* downloaded on the x86 machine on given location in PCAT tool from
> the target device, more about this can be found in qualcomm minidump guide patch.

I tried to apply this series on top of 535a265d7f0dd50 (as suggested by
`b4 am -l -g`), but it conflicts on patch [04/17]. Please specify the
exact base commit or another series for which this series is based on.


An old man doll... just what I always wanted! - Clara

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