#include <syscall.h>
       #include <linux/unwind.h>

       long getunwind(void *buf, size_t buf_size);

       Note: There is no glibc wrapper for this system call; see NOTES.

       Note: this function is obsolete.

       The  IA-64-specific  getunwind()  system  call copies the kernel's call
       frame unwind data into the buffer pointed to by  buf  and  returns  the
       size of the unwind data; this data describes the gate page (kernel code
       that is mapped into user space).

       The size of the buffer buf is  specified  in  buf_size.   The  data  is
       copied  only  if  buf_size  is greater than or equal to the size of the
       unwind data and buf is not NULL; otherwise, no data is copied, and  the
       call  succeeds,  returning  the  size that would be needed to store the
       unwind data.

       The first part of the unwind data contains an unwind table.   The  rest
       contains  the  associated  unwind  information, in no particular order.
       The unwind table contains entries of the following form:

            u64 start;      (64-bit address of start of function)
            u64 end;        (64-bit address of end of function)
            u64 info;       (BUF-relative offset to unwind info)

       An entry whose start value is zero indicates the end of the table.  For
       more  information  about the format, see the IA-64 Software Conventions
       and Runtime Architecture manual.

       On success, getunwind() returns the size of unwind table.  On error, -1
       is returned and errno is set to indicate the error.

       getunwind()  fails  with  the  error EFAULT if the unwind info can't be
       stored in the space specified by buf.

       This system call is available since Linux 2.4.

       This system call is Linux specific, and is available only on the  IA-64

       This  system  call  has  been deprecated.  The modern way to obtain the
       kernel's unwind data is via the gate  DSO.   The  address  of  the  ELF
       header  for  this  DSO is passed to user level via AT_SYSINFO_EHDR (see

Linux                             2013-02-13                      GETUNWIND(2)
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