CVS commit: [netbsd-5] src/sys/arch/xen/xen

["Jeff Rizzo" <riz%netbsd.org@localhost>]

Module Name:    src
Committed By:   riz
Date:           Sun Nov 21 23:55:58 UTC 2010

Modified Files:
        src/sys/arch/xen/xen [netbsd-5]: if_xennet_xenbus.c

Log Message:
Pull up following revision(s) (requested by jym in ticket #1473):
        sys/arch/xen/xen/if_xennet_xenbus.c: revision 1.42
        sys/arch/xen/xen/if_xennet_xenbus.c: revision 1.43
        sys/arch/xen/xen/if_xennet_xenbus.c: revision 1.45
Features (like feature-rx-copy) are set during XenbusStateInitWait in
backend. So delay xennet_xenbus_resume() up to notification of
backend state change.
This avoids a race that happens during dynamic attach/detach of network
interfaces with xm(1), where frontend queries xenstore for features not
yet reported by backend. This does not happen during normal domU boot,
as the backend has enough time to fill in these entries before frontend
asks for them.
Issue was reported by sborrill@: detaching xennet interfaces with RX copy
mode enabled turns them back during attach to RX flip mode due to the race.
feature-rx-copy support is part of another patch.
Handle error case (avoid changing to XenbusStateConnected when resume
failed)
Implement feature-rx-copy support in xennet (domU network frontend).
Instead of flipping pages back and forth between dom0 and domU for the
network RX queue, feature-rx-copy tells frontend to use content copy
instead.
This is the only mode supported by the dom0 Linux pv_ops backend. NetBSD
domU and dom0 can still fall back to flipping, when needed.
Copy is supposed to be faster than flipping, as it does not require
MMU manipulation and TLB shootdowns.
Based on patch provided by Hideki ONO. Thanks!
See also http://mail-index.netbsd.org/port-xen/2010/09/24/msg006265.html
and http://mail-index.netbsd.org/port-xen/2010/10/16/msg006312.html
ok bouyer@.
XXX will ask for a pull-up after 5.1 is branched.


To generate a diff of this commit:
cvs rdiff -u -r1.29.2.3 -r1.29.2.4 src/sys/arch/xen/xen/if_xennet_xenbus.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.