Search notes:

oradebug call

oradebug call can be used to call an internal function. 
SYS> oradebug help call
CALL           [-t count] <func> [arg1]...[argn] Invoke function with arguments

SYS> oradebug call ksmget_sgamaxalloc
Function returned 3CBF40

SYS> oradebug call ksmgsizeof_granule
Function returned 400000

Execute cmd.exe command on Windows

oradebug call system "dir>oradebug.out"
Find file in c:\…\…\database directory: 
C:\> dir c:\…\…\datbase\oradebug*

Calling clib functions

At least on Windows, standard c library functions can be called: 
SQL> oradebug call abs     -42
SQL> oradebug call strnlen "foobarbaz"

ORA-07443: function … not found

Trying to call a function that is not known by oradebug causes the error message ORA-07443 (function … not found) to be thrown.
Thus, it is possible to dump the call stack when this error is thrown with something like 
oradebug setmypid
oradebug event 7443 trace("ORA-07443: %\n", shortstack())
oradebug call  doesNotExist
oradebug tracefile_name
On Windows, Oracle 19, the callstack is
Instead of using the shortstack() action, it is also possible to call 
oradebug event 7443 callstack(1)

Misc

dbkedDefDump

dbkedDefDump seems to the function that performs oradebug core (compare both in tracefile). 
oradebug call dbkedDefDump

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