UFFDIO_ZEROPAGE(2const) - Linux manual page (original) (raw)

UFFDIOZEROPAGE(2const) UFFDIOZEROPAGE(2const)

NAME top

   UFFDIO_ZEROPAGE - zero out a memory range registered with
   userfaultfd

LIBRARY top

   Standard C library (_libc_, _-lc_)

SYNOPSIS top

   **#include <linux/userfaultfd.h>** /* Definition of **UFFD*** constants */
   **#include <sys/ioctl.h>**

   **int ioctl(int** _fd_**, UFFDIO_ZEROPAGE, struct uffdio_zeropage ***_argp_**);**

   **#include <linux/userfaultfd.h>**

   **struct uffdio_zeropage {**
       **struct uffdio_range  range;**
       **__u64                mode;** /* Flags controlling behavior */
       **__s64                zeropage;** /* Number of bytes zeroed */
   **};**

DESCRIPTION top

   Zero out a memory range registered with userfaultfd.

   The following value may be bitwise ORed in _mode_ to change the
   behavior of the **UFFDIO_ZEROPAGE** operation:

   **UFFDIO_ZEROPAGE_MODE_DONTWAKE**
          Do not wake up the thread that waits for page-fault
          resolution.

   The _zeropage_ field is used by the kernel to return the number of
   bytes that was actually zeroed, or an error in the same manner as
   **UFFDIO_COPY**.  If the value returned in the _zeropage_ field doesn't
   match the value that was specified in _range.len_, the operation
   fails with the error **EAGAIN**.  The _zeropage_ field is output-only;
   it is not read by the **UFFDIO_ZEROPAGE** operation.

RETURN VALUE top

   This [ioctl(2)](../man2/ioctl.2.html) operation returns 0 on success.  In this case, the
   entire area was zeroed.  On error, -1 is returned and _[errno](../man3/errno.3.html)_ is set
   to indicate the error.

ERRORS top

   **EAGAIN** The number of bytes zeroed (i.e., the value returned in the
          _zeropage_ field) does not equal the value that was specified
          in the _range.len_ field.

   **EINVAL** Either _range.start_ or _range.len_ was not a multiple of the
          system page size; or _range.len_ was zero; or the range
          specified was invalid.

   **EINVAL** An invalid bit was specified in the _mode_ field.

   **ESRCH** (since Linux 4.13)
          The faulting process has exited at the time of a
          **UFFDIO_ZEROPAGE** operation.

STANDARDS top

   Linux.

HISTORY top

   Linux 4.3.

EXAMPLES top

   See [userfaultfd(2)](../man2/userfaultfd.2.html).

SEE ALSO top

   [ioctl(2)](../man2/ioctl.2.html), [ioctl_userfaultfd(2)](../man2/ioctl%5Fuserfaultfd.2.html), [userfaultfd(2)](../man2/userfaultfd.2.html)

   _linux.git/Documentation/admin-guide/mm/userfaultfd.rst_

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Linux man-pages 6.10 2024-07-23 UFFDIOZEROPAGE(2const)

Pages that refer to this page:ioctl_userfaultfd(2)