GETUNWIND(2)              (2017-09-15)               GETUNWIND(2)

     NAME
          getunwind - copy the unwind data to caller's buffer

     SYNOPSIS
          #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.

     DESCRIPTION
          Note: this function is obsolete.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.

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

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

     VERSIONS

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     GETUNWIND(2)              (2017-09-15)               GETUNWIND(2)

          This system call is available since Linux 2.4.

     CONFORMING TO
          This system call is Linux-specific, and is available only on
          the IA-64 architecture.

     NOTES
          This system call has been deprecated.  The modern way to
          obtain the kernel's unwind data is via the vdso(7).

          Glibc does not provide a wrapper for this system call; in
          the unlikely event that you want to call it, use syscall(2).

     SEE ALSO
          getauxval(3)

     COLOPHON
          This page is part of release 5.10 of the Linux man-pages
          project.  A description of the project, information about
          reporting bugs, and the latest version of this page, can be
          found at https://www.kernel.org/doc/man-pages/.

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