[Crash-utility] is crash 7.1.8 meant to support CONFIG_DEBUG_INFO_SPLIT=y / CONFIG_DEBUG_INFO_DWARF4=y kernel builds?

[Jason Vas Dias]

Hi -
I have these kernel config options set for a successful kernel build :

$ grep DEBUG_INFO .config
CONFIG_DEBUG_INFO=y
# CONFIG_DEBUG_INFO_REDUCED is not set
CONFIG_DEBUG_INFO_SPLIT=y
CONFIG_DEBUG_INFO_DWARF4=y

This splits debug_info sections into separate ${X}.dwo files for each kernel
object produced.

I modified several files and did a 'make bzImage' ,  which succeeded,
and installed the kernel, and tried to run crash-7.1.8 to inspect a
few things, but it says:
<quote><pre>
$ crash vmlinuz /proc/kcore
....
gdb called without error_hook: Dwarf Error: wrong version in
compilation unit header (is 0, should be 2, 3, or 4) [in module
/usr/build/linux/linux-4.10/arch/x86/kernel/head64.dwo]
Dwarf Error: wrong version in compilation unit header (is 0, should be
2, 3, or 4) [in module
/usr/build/linux/linux-4.10/arch/x86/kernel/head64.dwo]

crash: vmlinux: no debugging data available
</pre></quote>

But the files still exist from the build:
-rw-r--r-- 1 root root 47784 Feb 21 20:07
/usr/build/linux/linux-4.10/arch/x86/kernel/head64.dwo
-rw-r--r-- 1 root root 17072 Feb 21 20:07
/usr/build/linux/linux-4.10/arch/x86/kernel/head64.o
in the same directory as the head64.c file .

I thought the whole point of 'vmlinux' was that it contained the debug_info ?
Do I need to re-link a vmlinux.dbg with all the *.dwo files
corresponding to each '*.o' file vmlinux contains , and vmlinux?
If so, then I don't see much point in the 'CONFIG_DEBUG_INFO_SPLIT=y'
option. Shouldn't a 'vmlinux.dwo' file be produced, containing all
concatenated
debug_info sections for 'vmlinux' ?
I guess crash just doesn't support
CONFIG_DEBUG_INFO_SPLIT=y / CONFIG_DEBUG_INFO_DWARF4=y ?

Sorry for the newbie type question.  Please respond to :
  jason.vas.dias at gmail.com
I'm not a member of the list.

Thanks & Regards,
Jason