[Crash-utility] Re: Read orc_header section to detect ORC version
On 2024/01/30 9:24, nilayvaish(a)google.com wrote:
Folks
The Linux kernel commit b9f174c811e3ae4ae8959dc57e6adb9990e913f4
(https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit...)
added an ELF section for the ORC version identifier. I think the crash utility should use
this section to identify the ORC version in use.
I want to implement this feature in the crash utility. As I understand it, we would need
to read the kernel binary first, find out whether it has .orc_header section and then read
the section to figure out the version of the ORC format in use.
thanks for the information.
I can see that there is the orc_header symbol and data also in a vmcore,
so maybe it can be read easily:
crash> whatis orc_header
const u8 orc_header[20];
crash> rd -8 orc_header 20
ffffffffb718ef94: fe 5d 32 bf 58 1b d6 3b 2c a9 a5 c6 5b a5 a6 25 ...
ffffffffb718efa4: ea b3 fe 24
but it's a hash, not a version number, how are you going to use this?
Does crash have to have all historical hash values? all of format
changes do not affect crash's unwinder though.
Thanks,
Kazu
>
> I do not have familiarity with the code for the crash utility. Is it possible for
someone to advise on whether the above sounds reasonable? If yes, then how to divide the
functionality among the files? If no, then what would a reasonable to have this
functionality?
>
> Thanks!
> --
> Crash-utility mailing list -- devel(a)lists.crash-utility.osci.io
> To unsubscribe send an email to devel-leave(a)lists.crash-utility.osci.io
> https://${domain_name}/admin/lists/devel.lists.crash-utility.osci.io/
> Contribution Guidelines: https://github.com/crash-utility/crash/wiki