Hi, when do migration test, we hit the panic as below: <1>BUG: unable to handle kernel paging request at 0000000b819fdb98 <1>IP: [<ffffffff812a588f>] notify_remote_via_irq+0x13/0x34 <4>PGD 94b10067 PUD 0 <0>Oops: 0000 [#1] SMP <0>last sysfs file: /sys/class/misc/autofs/dev <4>CPU 3 <4>Modules linked in: autofs4(U) hidp(U) nfs(U) fscache(U) nfs_acl(U) auth_rpcgss(U) rfcomm(U) l2cap(U) bluetooth(U) rfkill(U) lockd(U) sunrpc(U) nf_conntrack_netbios_ns(U) ipt_REJECT(U) nf_conntrack_ipv4(U) nf_defrag_ipv4(U) xt_state(U) nf_conntrack(U) iptable_filter(U) ip_tables(U) ip6t_REJECT(U) xt_tcpudp(U) ip6table_filter(U) ip6_tables(U) x_tables(U) ipv6(U) parport_pc(U) lp(U) parport(U) snd_seq_dummy(U) snd_seq_oss(U) snd_seq_midi_event(U) snd_seq(U) snd_seq_device(U) snd_pcm_oss(U) snd_mixer_oss(U) snd_pcm(U) snd_timer(U) snd(U) soundcore(U) snd_page_alloc(U) joydev(U) xen_netfront(U) pcspkr(U) xen_blkfront(U) uhci_hcd(U) ohci_hcd(U) ehci_hcd(U) Pid: 18, comm: events/3 Not tainted 2.6.32 RIP: e030:[<ffffffff812a588f>] [<ffffffff812a588f>] ify_remote_via_irq+0x13/0x34 RSP: e02b:ffff8800e7bf7bd0 EFLAGS: 00010202 RAX: ffff8800e61c8000 RBX: ffff8800e62f82c0 RCX: 0000000000000000 RDX: 00000000000001e3 RSI: ffff8800e7bf7c68 RDI: 0000000bfffffff4 RBP: ffff8800e7bf7be0 R08: 00000000000001e2 R09: ffff8800e62f82c0 R10: 0000000000000001 R11: ffff8800e6386110 R12: 0000000000000000 R13: 0000000000000007 R14: ffff8800e62f82e0 R15: 0000000000000240 FS: 00007f409d3906e0(0000) GS:ffff8800028b8000(0000) GS:0000000000000000 CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000b819fdb98 CR3: 000000003ee3b000 CR4: 0000000000002660 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process events/3 (pid: 18, threadinfo ffff8800e7bf6000, task f8800e7bf4540) Stack: 0000000000000200 ffff8800e61c8000 ffff8800e7bf7c00 ffffffff812712c9 <0> ffffffff8100ea5f ffffffff81438d80 ffff8800e7bf7cd0 ffffffff812714ee <0> 0000000000000000 ffffffff81270568 000000000000e030 0000000000010202 Call Trace: [<ffffffff812712c9>] xenfb_send_event+0x5c/0x5e [<ffffffff8100ea5f>] ? xen_restore_fl_direct_end+0x0/0x1 [<ffffffff81438d80>] ? _spin_unlock_irqrestore+0x16/0x18 [<ffffffff812714ee>] xenfb_refresh+0x1b1/0x1d7 [<ffffffff81270568>] ? sys_imageblit+0x1ac/0x458 [<ffffffff81271786>] xenfb_imageblit+0x2f/0x34 [<ffffffff8126a3e5>] soft_cursor+0x1b5/0x1c8 [<ffffffff8126a137>] bit_cursor+0x4b6/0x4d7 [<ffffffff8100ea5f>] ? xen_restore_fl_direct_end+0x0/0x1 [<ffffffff81438d80>] ? _spin_unlock_irqrestore+0x16/0x18 [<ffffffff81269c81>] ? bit_cursor+0x0/0x4d7 [<ffffffff812656b7>] fb_flashcursor+0xff/0x111 [<ffffffff812655b8>] ? fb_flashcursor+0x0/0x111 [<ffffffff81071812>] worker_thread+0x14d/0x1ed [<ffffffff81075a8c>] ? autoremove_wake_function+0x0/0x3d [<ffffffff81438d80>] ? _spin_unlock_irqrestore+0x16/0x18 [<ffffffff810716c5>] ? worker_thread+0x0/0x1ed [<ffffffff810756e3>] kthread+0x6e/0x76 [<ffffffff81012dea>] child_rip+0xa/0x20 [<ffffffff81011fd1>] ? int_ret_from_sys_call+0x7/0x1b [<ffffffff8101275d>] ? retint_restore_args+0x5/0x6 [<ffffffff81012de0>] ? child_rip+0x0/0x20 Code: 6b ff 0c 8b 87 a4 db 9f 81 66 85 c0 74 08 0f b7 f8 e8 3b ff ff ff c9 c3 55 48 89 e5 48 83 ec 10 0f 1f 44 00 00 89 ff 48 6b ff 0c <8b> 87 a4 db 9f 81 66 85 c0 74 14 48 8d 75 f0 0f b7 c0 bf 04 00 RIP [<ffffffff812a588f>] notify_remote_via_irq+0x13/0x34 RSP <ffff8800e7bf7bd0> CR2: 0000000b819fdb98 ---[ end trace 098b4b74827595d0 ]--- The root cause of the panic is try to refresh xenfb when suspend/resume. Clear refresh flag of xenfb before disconnect backend would fix this issue. Also below patch will fixed mem leak when connect to xenfb backend failed. Please review and comment. Signed-off-by: Joe Jin <joe.jin@oracle.com> Tested-by: Gurudas Pai <gurudas.pai@oracle.com> Cc: Ian Campbell <ian.campbell@citrix.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Andrew Morton <akpm@linux-foundation.org> --- xen-fbfront.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/drivers/video/xen-fbfront.c b/drivers/video/xen-fbfront.c index dc72563..6f23797 100644 --- a/drivers/video/xen-fbfront.c +++ b/drivers/video/xen-fbfront.c @@ -561,26 +561,24 @@ static void xenfb_init_shared_page(struct xenfb_info *info, static int xenfb_connect_backend(struct xenbus_device *dev, struct xenfb_info *info) { - int ret, evtchn; + int ret, evtchn, irq; struct xenbus_transaction xbt; ret = xenbus_alloc_evtchn(dev, &evtchn); if (ret) return ret; - ret = bind_evtchn_to_irqhandler(evtchn, xenfb_event_handler, + irq = bind_evtchn_to_irqhandler(evtchn, xenfb_event_handler, 0, dev->devicetype, info); - if (ret < 0) { + if (irq < 0) { xenbus_free_evtchn(dev, evtchn); xenbus_dev_fatal(dev, ret, "bind_evtchn_to_irqhandler"); - return ret; + return irq; } - info->irq = ret; - again: ret = xenbus_transaction_start(&xbt); if (ret) { xenbus_dev_fatal(dev, ret, "starting transaction"); - return ret; + goto unbind_irq; } ret = xenbus_printf(xbt, dev->nodename, "page-ref", "%lu", virt_to_mfn(info->page)); @@ -602,20 +600,27 @@ static int xenfb_connect_backend(struct xenbus_device *dev, if (ret == -EAGAIN) goto again; xenbus_dev_fatal(dev, ret, "completing transaction"); - return ret; + goto unbind_irq; } xenbus_switch_state(dev, XenbusStateInitialised); + info->irq = irq; return 0; error_xenbus: xenbus_transaction_end(xbt, 1); xenbus_dev_fatal(dev, ret, "writing xenstore"); + unbind_irq: + printk(KERN_ERR "xenfb_connect_backend failed!\n"); + unbind_from_irqhandler(irq, info); + xenbus_free_evtchn(dev, evtchn); return ret; } static void xenfb_disconnect_backend(struct xenfb_info *info) { + /* Prevent refresh xenfb */ + info->update_wanted = 0; if (info->irq >= 0) unbind_from_irqhandler(info->irq, info); info->irq = -1; _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Ian Campbell
2011-Jan-07 09:17 UTC
[Xen-devel] Re: [patch] xenfb: fix xenfb suspend/resume race.
On Fri, 2011-01-07 at 06:40 +0000, Joe Jin wrote:> Hi, > > when do migration test, we hit the panic as below: > <1>BUG: unable to handle kernel paging request at 0000000b819fdb98 > <1>IP: [<ffffffff812a588f>] notify_remote_via_irq+0x13/0x34 > <4>PGD 94b10067 PUD 0 > <0>Oops: 0000 [#1] SMP > <0>last sysfs file: /sys/class/misc/autofs/dev > <4>CPU 3 > <4>Modules linked in: autofs4(U) hidp(U) nfs(U) fscache(U) nfs_acl(U) > auth_rpcgss(U) rfcomm(U) l2cap(U) bluetooth(U) rfkill(U) lockd(U) sunrpc(U) > nf_conntrack_netbios_ns(U) ipt_REJECT(U) nf_conntrack_ipv4(U) > nf_defrag_ipv4(U) xt_state(U) nf_conntrack(U) iptable_filter(U) ip_tables(U) > ip6t_REJECT(U) xt_tcpudp(U) ip6table_filter(U) ip6_tables(U) x_tables(U) > ipv6(U) parport_pc(U) lp(U) parport(U) snd_seq_dummy(U) snd_seq_oss(U) > snd_seq_midi_event(U) snd_seq(U) snd_seq_device(U) snd_pcm_oss(U) > snd_mixer_oss(U) snd_pcm(U) snd_timer(U) snd(U) soundcore(U) > snd_page_alloc(U) joydev(U) xen_netfront(U) pcspkr(U) xen_blkfront(U) > uhci_hcd(U) ohci_hcd(U) ehci_hcd(U) > Pid: 18, comm: events/3 Not tainted 2.6.32 > RIP: e030:[<ffffffff812a588f>] [<ffffffff812a588f>] > ify_remote_via_irq+0x13/0x34 > RSP: e02b:ffff8800e7bf7bd0 EFLAGS: 00010202 > RAX: ffff8800e61c8000 RBX: ffff8800e62f82c0 RCX: 0000000000000000 > RDX: 00000000000001e3 RSI: ffff8800e7bf7c68 RDI: 0000000bfffffff4 > RBP: ffff8800e7bf7be0 R08: 00000000000001e2 R09: ffff8800e62f82c0 > R10: 0000000000000001 R11: ffff8800e6386110 R12: 0000000000000000 > R13: 0000000000000007 R14: ffff8800e62f82e0 R15: 0000000000000240 > FS: 00007f409d3906e0(0000) GS:ffff8800028b8000(0000) > GS:0000000000000000 > CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b > CR2: 0000000b819fdb98 CR3: 000000003ee3b000 CR4: 0000000000002660 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 > Process events/3 (pid: 18, threadinfo ffff8800e7bf6000, task > f8800e7bf4540) > Stack: > 0000000000000200 ffff8800e61c8000 ffff8800e7bf7c00 ffffffff812712c9 > <0> ffffffff8100ea5f ffffffff81438d80 ffff8800e7bf7cd0 ffffffff812714ee > <0> 0000000000000000 ffffffff81270568 000000000000e030 0000000000010202 > Call Trace: > [<ffffffff812712c9>] xenfb_send_event+0x5c/0x5e > [<ffffffff8100ea5f>] ? xen_restore_fl_direct_end+0x0/0x1 > [<ffffffff81438d80>] ? _spin_unlock_irqrestore+0x16/0x18 > [<ffffffff812714ee>] xenfb_refresh+0x1b1/0x1d7 > [<ffffffff81270568>] ? sys_imageblit+0x1ac/0x458 > [<ffffffff81271786>] xenfb_imageblit+0x2f/0x34 > [<ffffffff8126a3e5>] soft_cursor+0x1b5/0x1c8 > [<ffffffff8126a137>] bit_cursor+0x4b6/0x4d7 > [<ffffffff8100ea5f>] ? xen_restore_fl_direct_end+0x0/0x1 > [<ffffffff81438d80>] ? _spin_unlock_irqrestore+0x16/0x18 > [<ffffffff81269c81>] ? bit_cursor+0x0/0x4d7 > [<ffffffff812656b7>] fb_flashcursor+0xff/0x111 > [<ffffffff812655b8>] ? fb_flashcursor+0x0/0x111 > [<ffffffff81071812>] worker_thread+0x14d/0x1ed > [<ffffffff81075a8c>] ? autoremove_wake_function+0x0/0x3d > [<ffffffff81438d80>] ? _spin_unlock_irqrestore+0x16/0x18 > [<ffffffff810716c5>] ? worker_thread+0x0/0x1ed > [<ffffffff810756e3>] kthread+0x6e/0x76 > [<ffffffff81012dea>] child_rip+0xa/0x20 > [<ffffffff81011fd1>] ? int_ret_from_sys_call+0x7/0x1b > [<ffffffff8101275d>] ? retint_restore_args+0x5/0x6 > [<ffffffff81012de0>] ? child_rip+0x0/0x20 > Code: 6b ff 0c 8b 87 a4 db 9f 81 66 85 c0 74 08 0f b7 f8 e8 3b ff ff ff c9 > c3 55 48 89 e5 48 83 ec 10 0f 1f 44 00 00 89 ff 48 6b ff 0c <8b> 87 a4 db 9f > 81 66 85 c0 74 14 48 8d 75 f0 0f b7 c0 bf 04 00 > RIP [<ffffffff812a588f>] notify_remote_via_irq+0x13/0x34 > RSP <ffff8800e7bf7bd0> > CR2: 0000000b819fdb98 > ---[ end trace 098b4b74827595d0 ]--- > > The root cause of the panic is try to refresh xenfb when suspend/resume.perhaps work "... between the resume and reconnecting to the backend." into that sentence somewhere.> Clear refresh flag of xenfb before disconnect backend would fix this issue.s/refresh/update_wanted/> Also below patch will fixed mem leak when connect to xenfb backend failed. > > Please review and comment. > > Signed-off-by: Joe Jin <joe.jin@oracle.com> > Tested-by: Gurudas Pai <gurudas.pai@oracle.com>Looks good. But please separate the mem leak fix into its own patch, it has nothing to do with this crash (hiding a 1 line fix for a crash in amongst 30 lines of something else does nobody any favours, as the length of this thread testifies). You can add Acked-by: Ian Campbell <ian.campbell@citrix.com> to the xenfb_disconnect_backend change once you''ve split it out. I have some further comments on the xenfb_connect_backend change below.> Cc: Jeremy Fitzhardinge <jeremy@goop.org> > Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > > --- > xen-fbfront.c | 21 +++++++++++++-------- > 1 file changed, 13 insertions(+), 8 deletions(-) > > diff --git a/drivers/video/xen-fbfront.c b/drivers/video/xen-fbfront.c > index dc72563..6f23797 100644 > --- a/drivers/video/xen-fbfront.c > +++ b/drivers/video/xen-fbfront.c > @@ -561,26 +561,24 @@ static void xenfb_init_shared_page(struct xenfb_info *info, > static int xenfb_connect_backend(struct xenbus_device *dev, > struct xenfb_info *info) > { > - int ret, evtchn; > + int ret, evtchn, irq; > struct xenbus_transaction xbt; > > ret = xenbus_alloc_evtchn(dev, &evtchn); > if (ret) > return ret; > - ret = bind_evtchn_to_irqhandler(evtchn, xenfb_event_handler, > + irq = bind_evtchn_to_irqhandler(evtchn, xenfb_event_handler, > 0, dev->devicetype, info); > - if (ret < 0) { > + if (irq < 0) { > xenbus_free_evtchn(dev, evtchn); > xenbus_dev_fatal(dev, ret, "bind_evtchn_to_irqhandler"); > - return ret; > + return irq; > } > - info->irq = ret; > - > again: > ret = xenbus_transaction_start(&xbt); > if (ret) { > xenbus_dev_fatal(dev, ret, "starting transaction"); > - return ret; > + goto unbind_irq; > } > ret = xenbus_printf(xbt, dev->nodename, "page-ref", "%lu", > virt_to_mfn(info->page)); > @@ -602,20 +600,27 @@ static int xenfb_connect_backend(struct xenbus_device *dev, > if (ret == -EAGAIN) > goto again; > xenbus_dev_fatal(dev, ret, "completing transaction"); > - return ret; > + goto unbind_irq; > } > > xenbus_switch_state(dev, XenbusStateInitialised); > + info->irq = irq; > return 0; > > error_xenbus: > xenbus_transaction_end(xbt, 1); > xenbus_dev_fatal(dev, ret, "writing xenstore"); > + unbind_irq: > + printk(KERN_ERR "xenfb_connect_backend failed!\n");If anything this should be xenbus_dev_BLAH(). However all the places which "goto unbind_irq" already include a xenbus_dev_fatal with more specific context information and so does the case which falls through from error_xenbus so I think this new message is redundant.> + unbind_from_irqhandler(irq, info); > + xenbus_free_evtchn(dev, evtchn);unbind_from_irqhandler will also close the event channel for you so the call to xenbus_free_evtchn is not necessary here. Thanks, Ian. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Hi, when do migration test, we hit the panic as below: <1>BUG: unable to handle kernel paging request at 0000000b819fdb98 <1>IP: [<ffffffff812a588f>] notify_remote_via_irq+0x13/0x34 <4>PGD 94b10067 PUD 0 <0>Oops: 0000 [#1] SMP <0>last sysfs file: /sys/class/misc/autofs/dev <4>CPU 3 <4>Modules linked in: autofs4(U) hidp(U) nfs(U) fscache(U) nfs_acl(U) auth_rpcgss(U) rfcomm(U) l2cap(U) bluetooth(U) rfkill(U) lockd(U) sunrpc(U) nf_conntrack_netbios_ns(U) ipt_REJECT(U) nf_conntrack_ipv4(U) nf_defrag_ipv4(U) xt_state(U) nf_conntrack(U) iptable_filter(U) ip_tables(U) ip6t_REJECT(U) xt_tcpudp(U) ip6table_filter(U) ip6_tables(U) x_tables(U) ipv6(U) parport_pc(U) lp(U) parport(U) snd_seq_dummy(U) snd_seq_oss(U) snd_seq_midi_event(U) snd_seq(U) snd_seq_device(U) snd_pcm_oss(U) snd_mixer_oss(U) snd_pcm(U) snd_timer(U) snd(U) soundcore(U) snd_page_alloc(U) joydev(U) xen_netfront(U) pcspkr(U) xen_blkfront(U) uhci_hcd(U) ohci_hcd(U) ehci_hcd(U) Pid: 18, comm: events/3 Not tainted 2.6.32 RIP: e030:[<ffffffff812a588f>] [<ffffffff812a588f>] ify_remote_via_irq+0x13/0x34 RSP: e02b:ffff8800e7bf7bd0 EFLAGS: 00010202 RAX: ffff8800e61c8000 RBX: ffff8800e62f82c0 RCX: 0000000000000000 RDX: 00000000000001e3 RSI: ffff8800e7bf7c68 RDI: 0000000bfffffff4 RBP: ffff8800e7bf7be0 R08: 00000000000001e2 R09: ffff8800e62f82c0 R10: 0000000000000001 R11: ffff8800e6386110 R12: 0000000000000000 R13: 0000000000000007 R14: ffff8800e62f82e0 R15: 0000000000000240 FS: 00007f409d3906e0(0000) GS:ffff8800028b8000(0000) GS:0000000000000000 CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000b819fdb98 CR3: 000000003ee3b000 CR4: 0000000000002660 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process events/3 (pid: 18, threadinfo ffff8800e7bf6000, task f8800e7bf4540) Stack: 0000000000000200 ffff8800e61c8000 ffff8800e7bf7c00 ffffffff812712c9 <0> ffffffff8100ea5f ffffffff81438d80 ffff8800e7bf7cd0 ffffffff812714ee <0> 0000000000000000 ffffffff81270568 000000000000e030 0000000000010202 Call Trace: [<ffffffff812712c9>] xenfb_send_event+0x5c/0x5e [<ffffffff8100ea5f>] ? xen_restore_fl_direct_end+0x0/0x1 [<ffffffff81438d80>] ? _spin_unlock_irqrestore+0x16/0x18 [<ffffffff812714ee>] xenfb_refresh+0x1b1/0x1d7 [<ffffffff81270568>] ? sys_imageblit+0x1ac/0x458 [<ffffffff81271786>] xenfb_imageblit+0x2f/0x34 [<ffffffff8126a3e5>] soft_cursor+0x1b5/0x1c8 [<ffffffff8126a137>] bit_cursor+0x4b6/0x4d7 [<ffffffff8100ea5f>] ? xen_restore_fl_direct_end+0x0/0x1 [<ffffffff81438d80>] ? _spin_unlock_irqrestore+0x16/0x18 [<ffffffff81269c81>] ? bit_cursor+0x0/0x4d7 [<ffffffff812656b7>] fb_flashcursor+0xff/0x111 [<ffffffff812655b8>] ? fb_flashcursor+0x0/0x111 [<ffffffff81071812>] worker_thread+0x14d/0x1ed [<ffffffff81075a8c>] ? autoremove_wake_function+0x0/0x3d [<ffffffff81438d80>] ? _spin_unlock_irqrestore+0x16/0x18 [<ffffffff810716c5>] ? worker_thread+0x0/0x1ed [<ffffffff810756e3>] kthread+0x6e/0x76 [<ffffffff81012dea>] child_rip+0xa/0x20 [<ffffffff81011fd1>] ? int_ret_from_sys_call+0x7/0x1b [<ffffffff8101275d>] ? retint_restore_args+0x5/0x6 [<ffffffff81012de0>] ? child_rip+0x0/0x20 Code: 6b ff 0c 8b 87 a4 db 9f 81 66 85 c0 74 08 0f b7 f8 e8 3b ff ff ff c9 c3 55 48 89 e5 48 83 ec 10 0f 1f 44 00 00 89 ff 48 6b ff 0c <8b> 87 a4 db 9f 81 66 85 c0 74 14 48 8d 75 f0 0f b7 c0 bf 04 00 RIP [<ffffffff812a588f>] notify_remote_via_irq+0x13/0x34 RSP <ffff8800e7bf7bd0> CR2: 0000000b819fdb98 ---[ end trace 098b4b74827595d0 ]--- The root cause of race between the resume and reconnecting to the backend Clear update_wanted flag of xenfb before disconnect backend would fix this issue. Also below patch will fixed mem leak when connect to xenfb backend failed. Signed-off-by: Joe Jin <joe.jin@oracle.com> Tested-by: Gurudas Pai <gurudas.pai@oracle.com> Acked-by: Ian Campbell <ian.campbell@citrix.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Andrew Morton <akpm@linux-foundation.org> --- xen-fbfront.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/video/xen-fbfront.c b/drivers/video/xen-fbfront.c index dc72563..f2d9eb5 100644 --- a/drivers/video/xen-fbfront.c +++ b/drivers/video/xen-fbfront.c @@ -616,6 +616,8 @@ static int xenfb_connect_backend(struct xenbus_device *dev, static void xenfb_disconnect_backend(struct xenfb_info *info) { + /* Prevent xenfb refresh */ + info->update_wanted = 0; if (info->irq >= 0) unbind_from_irqhandler(info->irq, info); info->irq = -1; _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel