Re: [Crash-utility] [RFC 0/4] Add support to extract hardware device dumps from vmcore

----- Original Message ----- > Hi Dave, > > On Saturday, April 04/13/19, 2019 at 00:39:09 +0530, Dave Anderson wrote: > > > > Hi Surenda, > > > > Great -- I've been looking forward for this patch set to arrive. > > > > A couple things... > > > > First, I'm going to need two sample vmcores (one ELF, one compressed kdump) > > along with the associated vmlinux. You can contact me off-list with > > details > > on how we can arrange a transfer. > > > > Second, I do not want to add a new command. I rarely do so -- in fact, > > the only times since the original crash utility was released was in 2012, > > when the "ipcs" and "tree" commands were added in crash-6.0.7 and > > crash-6.0.8. > > New functionality is typically added as an option to an existing command. > > And in this case, the natural location to put it is in the existing "dev" > > command, and the devdump_extract() function can be moved into dev.c. > > (FWIW, you can add your Chelsio copyright at the top of that file) > > > > Ok, thanks for the suggestion. We will move the logic to dev command, > instead. > > We're thinking along the lines of following sample commands: > > Display the available device dumps > crash> dev -v > INDEX NAME OFFSET SIZE > 0 cxgb4_0000:02:00.4 0x278 33558464 > 1 cxgb4_0000:03:00.4 0x2001278 33558464 > > Extract device dump at specified index > crash> devdump -v 0 -f device_dump_0.bin > 33558464 bytes copied from 0x278 to device_dump_0.bin > > Let us know your thoughts. Hi Surenda, I've got your sample files -- thanks for them, I really appreciate it. Here are my thoughts... You probably want to make "-V" display the list of available device dumps in the vmcore, and make "-v <index>" select a singular device for dumping.

I also have a question re: the note contents. Is it up to the individual device as to what format the dump contents are made up of? Are they always binary dumps, or could a device dump ASCII log data or something to that effect?

I ask because I see that you are calling display_memory() using these arguments: void display_memory_from_file_offset(ulonglong addr, long count, void *opt) { display_memory(addr, count, DISPLAY_RAW | ASCII_ENDLINE | HEXADECIMAL, FILEADDR, opt); } Since you are using DISPLAY_RAW, display_memory() will simply copy the note data unmodified directly to the file, and the ASCII_ENDLINE and HEXADECIMAL arguments are ignored. So it's not clear why you added them?

But since you did, I'm now wondering whether it would be useful for a user to optionally dump a human-readable HEXADECIMAL/ASCII_ENDLINE formatted display of the data to the screen? If so, then perhaps if the "-v index" option is used alone *without* a file specified, why not just do a translated device dump to the screen?

So to summarize, my suggestions would be: dev -V dump the list of device dumps dev -v <index> [ -r file ] select and display one device dump, either in human-readable format to the screen by default, or optionally copy it raw to a file Thanks, Dave

> > > Third, there are some aesthetic changes that should be made in order > > to have the display use a more traditional output format like those > > used by other commands, e.g., with a single header with NAME, OFFSET and > > SIZE columns. > > > > Ok, We will fix this in next version. > > > Other than that, this looks good on paper! > > > > Thanks, > > Dave > > > > Thanks > Surendra > > > > > > ----- Original Message ----- > > > When kernel panic happens and kdump crash kernel is loaded, device > > > drivers enabled in the kdump crash kernel collect device specific > > > snapshot of the hardware/firmware state of their underlying devices. > > > These snapshots are exported as ELF notes with note type NT_VMCOREDD > > > (i.e., 0x700) in vmcore [1]. > > > > > > This series of patches enhance crash utility to analyze and > > > extract these hardware specific device dumps from vmcore using > > > a new "devdump" command. > > > > > > Patches 1 and 2 enhance help -D to parse NT_VMCOREDD ELF notes > > > in ELF vmcore and KDUMP vmcore, respectively. > > > > > > Patches 3 and 4 implement devdump command to analyze and extract > > > hardware specific device dumps from ELF vmcore and KDUMP vmcore, > > > respectively. > > > > > > Suggestions and feedback will be much appreciated. > > > > > > Thanks, > > > Surendra > > > > > > [1] https://lkml.org/lkml/2018/5/2/190 > > > > > > Surendra Mobiya (4): > > > parse NT_VMCOREDD ELF notes in ELF vmcore > > > parse NT_VMCOREDD ELF notes in KDUMP vmcore > > > add devdump command to extract NT_VMCOREDD from ELF vmcore > > > enhance devdump command to extract NT_VMCOREDD from KDUMP vmcore > > > > > > Makefile | 4 +-- > > > defs.h | 16 +++++++++ > > > devdump.c | 114 > > > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > > > diskdump.c | 71 +++++++++++++++++++++++++++++++++++- > > > global_data.c | 1 + > > > help.c | 23 ++++++++++++ > > > memory.c | 7 ++++ > > > netdump.c | 89 +++++++++++++++++++++++++++++++++++++++++++-- > > > netdump.h | 3 ++ > > > vmcore.h | 36 +++++++++++++++++++ > > > 10 files changed, 359 insertions(+), 5 deletions(-) > > > create mode 100644 devdump.c > > > create mode 100644 vmcore.h > > > > > > -- > > > 1.8.3.1 > > > > > > >