I don''t want my dom0 to update the clock in my HVM domU. I''ve already disabled network-based time synchronization inside the HVM. I''ve tried setting /proc/sys/xen/independent_wallclock=1 and then restarting xend, but the guest still gets the correct time. Any ideas on how to accomplish this? Steve Brueckner, ATC-NY _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> -----Original Message----- > From: xen-users-bounces@lists.xensource.com > [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of > Steve Brueckner > Sent: 06 March 2007 23:31 > To: xen-users@lists.xensource.com > Subject: [Xen-users] Desynchronize clock > > I don''t want my dom0 to update the clock in my HVM domU. I''ve already > disabled network-based time synchronization inside the HVM. > I''ve tried > setting /proc/sys/xen/independent_wallclock=1 and then > restarting xend, but > the guest still gets the correct time.Did you set independent wallclock in the guest or on Dom0? You should set it on guest, as that''s "who" should have a different clock to Dom0, right? It''s a per-domain settings, so individual domains are allowed to be either independent or "same". -- Mats> > Any ideas on how to accomplish this? > > Steve Brueckner, ATC-NY > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users > > >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Petersson, Mats wrote:>> -----Original Message----- >> I don''t want my dom0 to update the clock in my HVM domU. I''ve >> already disabled network-based time synchronization inside the HVM. >> I''ve tried >> setting /proc/sys/xen/independent_wallclock=1 and then restarting >> xend, but the guest still gets the correct time. > > Did you set independent wallclock in the guest or on Dom0? You should > set it on guest, as that''s "who" should have a different clock to > Dom0, right? It''s a per-domain settings, so individual domains are > allowed to be either independent or "same". >Ah, good point. Unfortunately, the guest is Windows, so there is no /proc/sys/xen/independent_wallclock setting inside the HVM. What I need is a way to tell domU which domains should be given access to the system or hardware clocks. In a recent, related post, someone said that for HVMs, "Dom0 time has no bearing to the guest''s time." However, every time I reboot the Windows HVM it has the correct time. Since I''ve disabled network-based time synch inside the Windows HVM, I have to assume it''s getting the time from either dom0''s system clock or from the hardware clock on the motherboard, no? Steve Brueckner, ATC-NY _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
As part of a security research project, I''m experimenting with capabilities of HVMs to test malware. There are a number of reasons for me wanting to control time within such a sandbox (e.g., jumping the clock or changing the clock speed to set off absolute or relative time-bombs). Steve Brueckner, ATC-NY -----Original Message----- From: Donofrio, Lewis [mailto:donofrio@umich.edu] Sent: Wednesday, March 07, 2007 1:10 PM To: Steve Brueckner Subject: RE: [Xen-users] Desynchronize clock Weird - might I ask why?> -----Original Message----- > From: xen-users-bounces@lists.xensource.com [mailto:xen-users- > bounces@lists.xensource.com] On Behalf Of Steve Brueckner > Sent: Tuesday, March 06, 2007 6:31 PM > To: xen-users@lists.xensource.com > Subject: [Xen-users] Desynchronize clock > > I don''t want my dom0 to update the clock in my HVM domU. I''ve already > disabled network-based time synchronization inside the HVM. I''vetried> setting /proc/sys/xen/independent_wallclock=1 and then restartingxend,> but > the guest still gets the correct time. > > Any ideas on how to accomplish this? > > Steve Brueckner, ATC-NY > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> -----Original Message----- > From: xen-users-bounces@lists.xensource.com > [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of > Steve Brueckner > Sent: 07 March 2007 18:11 > To: xen-users@lists.xensource.com > Subject: RE: [Xen-users] Desynchronize clock > > Petersson, Mats wrote: > >> -----Original Message----- > >> I don''t want my dom0 to update the clock in my HVM domU. I''ve > >> already disabled network-based time synchronization inside the HVM. > >> I''ve tried > >> setting /proc/sys/xen/independent_wallclock=1 and then restarting > >> xend, but the guest still gets the correct time. > > > > Did you set independent wallclock in the guest or on Dom0? > You should > > set it on guest, as that''s "who" should have a different clock to > > Dom0, right? It''s a per-domain settings, so individual domains are > > allowed to be either independent or "same". > > > > Ah, good point. Unfortunately, the guest is Windows, so there is no > /proc/sys/xen/independent_wallclock setting inside the HVM. What I > need is a way to tell domU which domains should be given > access to the > system or hardware clocks.Yes, someone else pointed out that it was a HVM guest after I''d written the reply (typical "did not read all of the important bit"). But indpendent_wallclock is really a per-domain setting anyways, so it''s not really right to set it in Dom0.> > In a recent, related post, someone said that for HVMs, "Dom0 time has > no bearing to the guest''s time." However, every time I reboot the > Windows HVM it has the correct time. Since I''ve disabled > network-based > time synch inside the Windows HVM, I have to assume it''s getting the > time from either dom0''s system clock or from the hardware > clock on the > motherboard, no?Actually, I think the time is kept by the virtual CMOS and Timer functionality in the HVM + QEMU-DM parts of Xen. You may be able to tweak those with some tools... I don''t think the tools exist today tho''. -- Mats> > Steve Brueckner, ATC-NY > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users > > >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On 7 Mar 2007 at 13:10, Steve Brueckner wrote:> In a recent, related post, someone said that for HVMs, "Dom0 time has > no bearing to the guest''s time." However, every time I reboot the > Windows HVM it has the correct time. Since I''ve disabled network-based > time synch inside the Windows HVM, I have to assume it''s getting the > time from either dom0''s system clock or from the hardware clock on the > motherboard, no? >Hi! I know it does not help you, but in VMware I see exactly the same: When starting a VM, the time displayed is correct, but when you don''t have "VMware tools set up for time sync", the clock is back half an hour or so within a few hours. A have a historical problem with clocks displaying the wrong time ;-) It''s an important issue that should be fixed. Regards, Ulrich _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On 3/8/07, Ulrich Windl <ulrich.windl@rz.uni-regensburg.de> wrote:> > I know it does not help you, but in VMware I see exactly the same: When > starting a > VM, the time displayed is correct, but when you don''t have "VMware tools > set up > for time sync", the clock is back half an hour or so within a few hours. > > A have a historical problem with clocks displaying the wrong time ;-)There is a good discussion of this here: http://rextang.net/blogs/work/archive/2006/12/21/4516.aspx and http://kb.vmware.com/KanisaPlatform/Publishing/329/1420_f.SAL_Public.html I''m not sure that Xen/HVM uses the similar method as vmware for time sync but I think one of the keys in increasing HZ. I''m not sure how at all HVM would work with clocks and windows. Maybe the PV drives have this functionality like vmware-tools. Nicholas _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users