Hi all, In a PV guest, shadow paging is used for logging dirty pages during live migration. For a HVM guest, it''s enabled all the time due to full virtualization. Does the current version of Xen support running a PV guest with shadow paging enabled all the time ? If so, will it work if I just put "shadow_memory = 8" in the cfg file ? Thanks. Regards, Levin Get all the Hottest Artists on Your Cell Phone - Plus 10 Bonus Tones Today! Find Your New Ringtone at Lycos Mobile. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Hi all, In a PV guest, shadow paging is used for logging dirty pages during live migration. For a HVM guest, it''s enabled all the time due to full virtualization. Does the current version of Xen support running a PV guest with shadow paging enabled all the time ? If so, will it work if I just put "shadow_memory = 8" in the cfg file ? Thanks. Regards, Levin Get all the Hottest Artists on Your Cell Phone - Plus 10 Bonus Tones Today! Find Your New Ringtone at Lycos Mobile. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Hi, In a PV guest, shadow paging is used for logging dirty pages during live migration. For a HVM guest, it''s enabled all the time due to full virtualization. Does the current version of Xen support running a PV guest with shadow paging enabled all the time ? If so, will it work if I just put "shadow_memory = 8" in the cfg file ? Thanks. Regards, Levin Get all the Hottest Artists on Your Cell Phone - Plus 10 Bonus Tones Today! Find Your New Ringtone at Lycos Mobile. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Hi, In a PV guest, shadow paging is used for logging dirty pages during live migration. For a HVM guest, it''s enabled all the time due to full virtualization. Does the current version of Xen support running a PV guest with shadow paging enabled all the time ? If so, will it work if I just put "shadow_memory = 8" in the cfg file ? Thanks. Regards, Levin Get all the Hottest Artists on Your Cell Phone - Plus 10 Bonus Tones Today! Find Your New Ringtone at Lycos Mobile. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
> In a PV guest, shadow paging is used for logging dirty pages during > live > migration. For a HVM guest, it's enabled all the time due to full > virtualization. > > Does the current version of Xen support running a PV guest with shadow > paging enabled all the time ? If so, will it work if I just put > "shadow_memory = 8" > in the cfg file ?During live relocation of PV guests, shadow mode is used to log dirty page accesses, but its not used to do address translation. It is possible to get PV guests running in 'auto translate mode', but I'm not sure it can be done via the guest config file. Since this mode is typically only used by various research projects its possible that support has rotted. Look for any references to auto translate mode in the domain builder for clues as to how to enable it. Ian _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On Sun, 2007-07-29 at 22:38 +0100, Ian Pratt wrote:> > In a PV guest, shadow paging is used for logging dirty pages during > > live > > migration. For a HVM guest, it''s enabled all the time due to full > > virtualization. > > > > Does the current version of Xen support running a PV guest with shadow > > paging enabled all the time ? If so, will it work if I just put > > "shadow_memory = 8" > > in the cfg file ? > > During live relocation of PV guests, shadow mode is used to log dirty > page accesses, but its not used to do address translation. It is > possible to get PV guests running in ''auto translate mode'', but I''m > not sure it can be done via the guest config file. Since this mode is > typically only used by various research projects its possible that > support has rotted. Look for any references to auto translate mode in > the domain builder for clues as to how to enable it.Adding features = "auto_translated_physmap|writable_page_tables" to the config file should add those features to the set passed to the guest. I can''t remember which set you would need to enable shadow mode, you may have to dig round in the builder and/or hypervisor to figure it out. However I''m not sure shadow mode (other than log-dirty) isn''t broken for PV guests. It''s been a long time since I tried it but it was broken back when the paravirt_ops tree was still trying to use it. Ian. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
At 07:34 +0100 on 30 Jul (1185780899), Ian Campbell wrote:> Adding > features = "auto_translated_physmap|writable_page_tables" > to the config file should add those features to the set passed to the > guest. I can''t remember which set you would need to enable shadow mode, > you may have to dig round in the builder and/or hypervisor to figure it > out.IIRC, "auto_translated_physmap" turns on both shadow mode and auto-translation. You could enable just the shadowing without the auto-translation by changing tools/libxc/xc_dom_x86.c to remove XEN_DOMCTL_SHADOW_ENABLE_TRANSLATE from the "mode" argument to xc_shadow_control().> However I''m not sure shadow mode (other than log-dirty) isn''t broken for > PV guests. It''s been a long time since I tried it but it was broken back > when the paravirt_ops tree was still trying to use it.Auto-translate was (briefly) fixed at that time too, but I''m quite sure it doesn''t work in the current tree. Some people had this kind of thing going for academic research projects; maybe one of them can comment. Cheers, Tim. -- Tim Deegan <Tim.Deegan@xensource.com>, XenSource UK Limited Registered office c/o EC2Y 5EB, UK; company number 05334508 _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
hi what is the auto_translated_physmap ?how does it work?and what about other mechanisms and how many mechanisms for paging are there in xen ? Thank you in advance Tim Deegan 写道:> At 07:34 +0100 on 30 Jul (1185780899), Ian Campbell wrote: > >> Adding >> features = "auto_translated_physmap|writable_page_tables" >> to the config file should add those features to the set passed to the >> guest. I can''t remember which set you would need to enable shadow mode, >> you may have to dig round in the builder and/or hypervisor to figure it >> out. >> > > IIRC, "auto_translated_physmap" turns on both shadow mode and > auto-translation. You could enable just the shadowing without the > auto-translation by changing tools/libxc/xc_dom_x86.c to remove > XEN_DOMCTL_SHADOW_ENABLE_TRANSLATE from the "mode" argument to > xc_shadow_control(). > > >> However I''m not sure shadow mode (other than log-dirty) isn''t broken for >> PV guests. It''s been a long time since I tried it but it was broken back >> when the paravirt_ops tree was still trying to use it. >> > > Auto-translate was (briefly) fixed at that time too, but I''m quite sure > it doesn''t work in the current tree. Some people had this kind of thing > going for academic research projects; maybe one of them can comment. > > Cheers, > > Tim. > >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Hi, At 19:01 +0800 on 22 Oct (1193079674), tgh wrote:> what is the auto_translated_physmap ?A shadow pagetable mode where Xen does the translation between guest-physical and machine-physical addresses for PV guests. Normally PV guests do that translation themselves, because it''s faster, and Xen does it for HVM guests because they can''t do it themseves.> how does it work?It doesn''t, at least not in xen-unstable. As I said, I believe some research projects have it working in their own trees because it''s useful for things like deterministic replay of guest execution.> and what about > other mechanisms and how many mechanisms for paging are there in xen ?Plenty. There are between two and eighteen shadow modes, depending on how you''d like to count them, hardware support for using two sets of pagetables at once, normal PV guest paging, writeable pagetables, grant tables for letting one guest see another guest''s pages, and IOMMU support for paging DMA. Probably one or two more in there somewhere. Tim. -- Tim Deegan <Tim.Deegan@xensource.com>, XenSource UK Limited Registered office c/o EC2Y 5EB, UK; company number 05334508 _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Hi, Tim Deegan, le Mon 22 Oct 2007 12:20:48 +0100, a écrit :> At 19:01 +0800 on 22 Oct (1193079674), tgh wrote: > > what is the auto_translated_physmap ? > > A shadow pagetable mode where Xen does the translation between > guest-physical and machine-physical addresses for PV guests. Normally > PV guests do that translation themselves, because it''s faster, and Xen > does it for HVM guests because they can''t do it themseves.It can be useful too for PV guests that don''t (want to) support PAE. Samuel _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
> > A shadow pagetable mode where Xen does the translation between > > guest-physical and machine-physical addresses for PV guests. Normally > > PV guests do that translation themselves, because it''s faster, and Xen > > does it for HVM guests because they can''t do it themseves. > > It can be useful too for PV guests that don''t (want to) support PAE.Are there any patches to allow this? I would find it quite useful. I''ve had the impression that most of the moving parts are already there but there''s not been sufficient impetus to tie them all together? Cheers, Mark -- Dave: Just a question. What use is a unicyle with no seat? And no pedals! Mark: To answer a question with a question: What use is a skateboard? Dave: Skateboards have wheels. Mark: My wheel has a wheel! _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Tim Deegan wrote:> A shadow pagetable mode where Xen does the translation between > guest-physical and machine-physical addresses for PV guests. Normally > PV guests do that translation themselves, because it''s faster, and Xen > does it for HVM guests because they can''t do it themseves. >I think we''ll need it to take advantage of NPT/EPT though, right? J _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
At 21:32 -0700 on 23 Oct (1193175163), Jeremy Fitzhardinge wrote:> Tim Deegan wrote: > > A shadow pagetable mode where Xen does the translation between > > guest-physical and machine-physical addresses for PV guests. Normally > > PV guests do that translation themselves, because it''s faster, and Xen > > does it for HVM guests because they can''t do it themseves. > > > > I think we''ll need it to take advantage of NPT/EPT though, right?The joy of NPT(VMI?)/EPT is that you don''t need shadow pagetables at all. :) Tim. -- Tim Deegan <Tim.Deegan@xensource.com>, XenSource UK Limited Registered office c/o EC2Y 5EB, UK; company number 05334508 _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Tim Deegan wrote:> The joy of NPT(VMI?)/EPT is that you don''t need shadow pagetables at > all. :) >Sure, but from a guest interface perspective they look the same. J _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On 24/10/07 11:00, "Jeremy Fitzhardinge" <jeremy@goop.org> wrote:> Tim Deegan wrote: >> The joy of NPT(VMI?)/EPT is that you don''t need shadow pagetables at >> all. :) >> > > Sure, but from a guest interface perspective they look the same.Would you want to take advantage of NPT/EPT once you''ve pv''ed your mmu interfaces? -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Keir Fraser wrote:> On 24/10/07 11:00, "Jeremy Fitzhardinge" <jeremy@goop.org> wrote: > > >> Tim Deegan wrote: >> >>> The joy of NPT(VMI?)/EPT is that you don''t need shadow pagetables at >>> all. :) >>> >>> >> Sure, but from a guest interface perspective they look the same. >> > > Would you want to take advantage of NPT/EPT once you''ve pv''ed your mmu > interfaces? >I think so. NPT/EPT would seem to have all the advantages of shadow paging and direct paging without the disadvantages. We would avoid taking faults/hypercalls on pagetable updates, and have the secondary benefit of not needing to worry about page permissions on pagetables, making it easier to use superpages for the kernel and in general. Perhaps the initial implementations will be sufficiently poor that it isn''t worth doing now, but I think it will in time. J _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Jeremy Fitzhardinge wrote:> Keir Fraser wrote: > > On 24/10/07 11:00, "Jeremy Fitzhardinge" <jeremy@goop.org> wrote: > > > > > > > Tim Deegan wrote: > > > > > > > The joy of NPT(VMI?)/EPT is that you don''t need shadowpagetables at> > > > all. :) > > > > > > > > > > > Sure, but from a guest interface perspective they look the same. > > > > > > > Would you want to take advantage of NPT/EPT once you''ve pv''ed yourmmu> > interfaces? > > > > I think so. NPT/EPT would seem to have all the advantages of shadow > paging and direct paging without the disadvantages. We would avoid > taking faults/hypercalls on pagetable updates, and have the secondary > benefit of not needing to worry about page permissions on pagetables, > making it easier to use superpages for the kernel and in general. > Perhaps the initial implementations will be sufficiently poor that it > isn''t worth doing now, but I think it will in time. > > JWell, then you need to run those in HVM domains ;-) Jun --- Intel Open Source Technology Center _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Nakajima, Jun wrote:> Well, then you need to run those in HVM domains ;-)Sure, but they can be a PV HVM domain. J _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel