Thanks Brian for your interest in this series.
On 2/23/2023 6:07 PM, Brian Masney wrote:
On Tue, Feb 21, 2023 at 04:55:07PM +0530, Mukesh Ojha wrote:
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 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 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.
I'd like to test this series plus your series that sets the multiple
download modes.
Sure, you are welcome, but for that you need a device running with
Qualcomm SoC and if it has a upstream support.
Also, testing of this patch needs some minimal out of tree patches and
i can help you with that.
Can you include documentation about how to actually use
this new feature?
Will surely do, Since this is still RFC, and i am doubtful on the path
of it in documentation directory.
Also the information that you provided above is really
useful. I think that should also go in the documentation file as well.
I already have a reliable way to make a board go BOOM and go into
ramdump mode.
That's very nice to hear; but again if you can specify your target
specification.
-Mukesh
Brian
