Message-ID: <ZP7VPfVtvbmB5aQf@debian.me>
Date:   Mon, 11 Sep 2023 15:52:13 +0700
From:   Bagas Sanjaya <bagasdotme@...il.com>
To:     Mukesh Ojha <quic_mojha@...cinc.com>, <corbet@....net>,
        <agross@...nel.org>, <andersson@...nel.org>,
        <konrad.dybcio@...aro.org>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <conor+dt@...nel.org>,
        <keescook@...omium.org>, <tony.luck@...el.com>,
        <gpiccoli@...lia.com>, <mathieu.poirier@...aro.org>,
        <catalin.marinas@....com>, <will@...nel.org>,
        <linus.walleij@...aro.org>, <andy.shevchenko@...il.com>,
        <vigneshr@...com>, <nm@...com>, <matthias.bgg@...il.com>,
        <kgene@...nel.org>, <alim.akhtar@...sung.com>,
        <bmasney@...hat.com>, <quic_tsoni@...cinc.com>
Cc:     <linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-hardening@...r.kernel.org>,
        <linux-remoteproc@...r.kernel.org>,
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        <linux-gpio@...r.kernel.org>, <linux-mediatek@...ts.infradead.org>,
        <linux-samsung-soc@...r.kernel.org>, <kernel@...cinc.com>
Subject: Re: [PATCH v5 00/17] Add Qualcomm Minidump kernel driver related
 support

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
> 
> https://lore.kernel.org/lkml/632c5b97-4a91-c3e8-1e6c-33d6c4f6454f@quicinc.com/
> 
> https://lore.kernel.org/lkml/695133e6-105f-de2a-5559-555cea0a0462@quicinc.com/
> 
> 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.
> 
> https://lore.kernel.org/lkml/0199db00-1b1d-0c63-58ff-03efae02cb21@quicinc.com/
> 
> 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,
> https://lore.kernel.org/lkml/1683561060-2197-1-git-send-email-quic_mojha@quicinc.com/
> 
> 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]
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/remoteproc/qcom_common.c#n142
> 
> 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: https://lore.kernel.org/lkml/1687955688-20809-1-git-send-email-quic_mojha@quicinc.com/
>  - 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
>    https://lore.kernel.org/lkml/1680076012-10785-1-git-send-email-quic_mojha@quicinc.com/
> 
> Changes in v3: https://lore.kernel.org/lkml/1683133352-10046-1-git-send-email-quic_mojha@quicinc.com/
>  - 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.
>     https://lore.kernel.org/lkml/1680076012-10785-1-git-send-email-quic_mojha@quicinc.com/
> 
> Changes in v2: https://lore.kernel.org/lkml/1679491817-2498-1-git-send-email-quic_mojha@quicinc.com/
>  - 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: https://lore.kernel.org/lkml/1676978713-7394-1-git-send-email-quic_mojha@quicinc.com/
> 
> 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.

Thanks.

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

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