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getunwind(2) — Linux manual page

getunwind(2)               System Calls Manualgetunwind(2)

NAME        top

       getunwind - copy the unwind data to caller's buffer

LIBRARY        top

       Standard C library (libc,-lc)

SYNOPSIS        top

#include <linux/unwind.h>#include <sys/syscall.h>/* Definition ofSYS_*constants */#include <unistd.h>[[deprecated]] long syscall(size_t buf_size;SYS_getunwind, voidbuf[buf_size],size_tbuf_size);

DESCRIPTION        top

Note: this system call is obsolete.       The IA-64-specificgetunwind() system call copies the kernel's       call frame unwind data into the buffer pointed to bybuf 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 bufferbuf is specified inbuf_size.  The data is       copied only ifbuf_size is greater than or equal to the size of       the unwind data andbuf 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 whosestart value is zero indicates the end of the table.       For more information about the format, see theIA-64 SoftwareConventions and Runtime Architecture manual.

RETURN VALUE        top

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

ERRORS        top

getunwind() fails with the errorEFAULTif the unwind info can't       be stored in the space specified bybuf.

STANDARDS        top

       Linux on IA-64.

HISTORY        top

       Linux 2.4.       This system call has been deprecated.  The modern way to obtain       the kernel's unwind data is via thevdso(7).

SEE ALSO        top

getauxval(3)

COLOPHON        top

       This page is part of theman-pages (Linux kernel and C library       user-space interface documentation) project.  Information about       the project can be found at        ⟨https://www.kernel.org/doc/man-pages/⟩.  If you have a bug report       for this manual page, see       ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.       This page was obtained from the tarball man-pages-6.15.tar.gz       fetched from       ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on       2025-08-11.  If you discover any rendering problems in this HTML       version of the page, or you believe there is a better or more up-       to-date source for the page, or you have corrections or       improvements to the information in this COLOPHON (which isnot       part of the original manual page), send a mail to       man-pages@man7.orgLinux man-pages 6.15            2025-06-28getunwind(2)

Pages that refer to this page:syscalls(2)

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