X-Git-Url: http://git.annexia.org/?p=libguestfs.git;a=blobdiff_plain;f=perl%2Flib%2FSys%2FGuestfs.pm;h=f8e6b7746bf35d10ca5be01513bb186fc25fca67;hp=cba0032517a3f5bf59db2ca30527f2f2a5acd099;hb=d1a1ab972bb22f4c38a21fcc73f81650aaa03b4e;hpb=bfdc03be234d6d95f18450846433bce4f97e184c

diff --git a/perl/lib/Sys/Guestfs.pm b/perl/lib/Sys/Guestfs.pm
index cba0032..f8e6b77 100644
--- a/perl/lib/Sys/Guestfs.pm
+++ b/perl/lib/Sys/Guestfs.pm
@@ -97,6 +97,11 @@ This function adds a virtual CD-ROM disk image to the guest.
 
 This is equivalent to the qemu parameter C<-cdrom filename>.
 
+Note that this call checks for the existence of C<filename>.  This
+stops you from specifying other types of drive which are supported
+by qemu such as C<nbd:> and C<http:> URLs.  To specify those, use
+the general C<$h-E<gt>config> call instead.
+
 =item $h->add_drive ($filename);
 
 This function adds a virtual machine disk image C<filename> to the
@@ -112,6 +117,30 @@ image).
 
 This is equivalent to the qemu parameter C<-drive file=filename>.
 
+Note that this call checks for the existence of C<filename>.  This
+stops you from specifying other types of drive which are supported
+by qemu such as C<nbd:> and C<http:> URLs.  To specify those, use
+the general C<$h-E<gt>config> call instead.
+
+=item $h->add_drive_ro ($filename);
+
+This adds a drive in snapshot mode, making it effectively
+read-only.
+
+Note that writes to the device are allowed, and will be seen for
+the duration of the guestfs handle, but they are written
+to a temporary file which is discarded as soon as the guestfs
+handle is closed.  We don't currently have any method to enable
+changes to be committed, although qemu can support this.
+
+This is equivalent to the qemu parameter
+C<-drive file=filename,snapshot=on>.
+
+Note that this call checks for the existence of C<filename>.  This
+stops you from specifying other types of drive which are supported
+by qemu such as C<nbd:> and C<http:> URLs.  To specify those, use
+the general C<$h-E<gt>config> call instead.
+
 =item $h->aug_close ();
 
 Close the current Augeas handle and free up any resources