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       Note: this function is obsolete.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

       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 gate DSO.  The address of the ELF header for this DSO is passed to  user  level
       via AT_SYSINFO_EHDR (see getauxval(3)).

       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 4.04 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 http://www.kernel.org/doc/man-pages/.