[PATCH 01/10] userfaultfd.2: briefly mention two-step feature handshake process

Axel Rasmussen
2023-09-19T19:02:19Z

This process is critical for programs which depend on extra features, so
it's worth mentioning here.

Future commits will much more fully describe it in ioctl_userfaultfd.2.

Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
---
man2/userfaultfd.2 | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/man2/userfaultfd.2 b/man2/userfaultfd.2
index 40354065c..1b2af22f9 100644
--- a/man2/userfaultfd.2
+++ b/man2/userfaultfd.2
@@ -200,8 +200,9 @@ the application must enable it using the
.B UFFDIO_API
.BR ioctl (2)
operation.
-This operation allows a handshake between the kernel and user space
-to determine the API version and supported features.
+This operation allows a two-step handshake between the kernel and user space
+to determine what API version and features the kernel supports,
+and then to enable those features user space wants.
This operation must be performed before any of the other
.BR ioctl (2)
operations described below (or those operations fail with the
--
2.42.0.459.ge4e396fd5e-goog