Author: kib Date: Sun Dec 16 01:51:38 2018 New Revision: 342144 URL: https://svnweb.freebsd.org/changeset/base/342144
Log: Document new required MI behaviour of pmap_enter(9) for CoW. Reviewed by: markj MFC after: 3 days Sponsored by: The FreeBSD Foundation Differential revision: https://reviews.freebsd.org/D18568 Modified: head/share/man/man9/pmap_enter.9 Modified: head/share/man/man9/pmap_enter.9 ============================================================================== --- head/share/man/man9/pmap_enter.9 Sun Dec 16 01:19:10 2018 (r342143) +++ head/share/man/man9/pmap_enter.9 Sun Dec 16 01:51:38 2018 (r342144) @@ -26,7 +26,7 @@ .\" .\" $FreeBSD$ .\" -.Dd February 16, 2018 +.Dd December 16, 2018 .Dt PMAP_ENTER 9 .Os .Sh NAME @@ -119,6 +119,14 @@ It is advised to clear for destroyed mappings if the implementation can ensure that no other writeable managed mappings for the previously mapped pages exist. +.Pp +If the request modifies an existing mapping to use a different physical +page, an implementation of +.Nm +must invalidate the previous mapping before installing the new one. +This ensures that all threads sharing the pmap keep a consistent +view of the mapping, which is necessary for the correct handling +of CoW (copy on write) faults. .Pp If the page .Fa m _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
