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> > I'm sort of wondering if missing PSE is the only issue I would face here.
> >
> > comparing c3-2 datascheet and xen sources/papers it seems that xen uses
> > following stuff that are misseed in c3-2
> >
> > 4mb pages
> > fast calls
> > page attribute table
> > virtual mode extension
> >
> > maybe some others.. although i'm not sure if any of those are critical for
> > correct operation of xen.... in particular that PAT seems worriesome.
> >
> > we already covered PSE, any comments on other features?
> >
>
> We don't use SYSCALL/SYSENTER, PAT or VME.

ah, good.




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My understanding was that PAT would likely be used to allow VMs to use
PSE, is that not correct?

-Kip

> > We don't use SYSCALL/SYSENTER, PAT or VME.
>
> ah, good.
>
>
>
>
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The two features are completely unrelated.

-- Keir

> My understanding was that PAT would likely be used to allow VMs to use
> PSE, is that not correct?
>
> -Kip
>
> > > We don't use SYSCALL/SYSENTER, PAT or VME.
> >
> > ah, good.
> >
> >
> >
> >
> > -------------------------------------------------------
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> > FREE OODBMS DOWNLOAD - A multidimensional database that combines
> > robust object and relational technologies, making it a perfect match
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> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/xen-devel
> >



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I was told there were security issues with allowing PSE in VMs outright.

-Kip

>
> The two features are completely unrelated.
>
> -- Keir
>
> > My understanding was that PAT would likely be used to allow VMs to use
> > PSE, is that not correct?
> >
> > -Kip
> >
> > > > We don't use SYSCALL/SYSENTER, PAT or VME.
> > >
> > > ah, good.
> > >
> > >
> > >
> > >
> > > -------------------------------------------------------
> > > This SF.Net email is sponsored by: InterSystems CACHE
> > > FREE OODBMS DOWNLOAD - A multidimensional database that combines
> > > robust object and relational technologies, making it a perfect match
> > > for Java, C++,COM, XML, ODBC and JDBC. www.intersystems.com/match8
> > > _______________________________________________
> > > Xen-devel mailing list
> > > Xen-devel@lists.sourceforge.net
> > > https://lists.sourceforge.net/lists/listinfo/xen-devel
> > >
>
>


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Ah yes, if VMs use PSE then we were plannign to abuse PAT to provide
some protection for us. However, VMs can *not* currently use PSE at
the moment and, even if they could, we have since discovered that our
abuse of PAT would not work anyway. :-)

-- Keir

>
> I was told there were security issues with allowing PSE in VMs outright.
>
> -Kip
>
> >
> > The two features are completely unrelated.
> >
> > -- Keir
> >
> > > My understanding was that PAT would likely be used to allow VMs to use
> > > PSE, is that not correct?
> > >
> > > -Kip
> > >
> > > > > We don't use SYSCALL/SYSENTER, PAT or VME.
> > > >
> > > > ah, good.
> > > >
> > > >
> > > >
> > > >
> > > > -------------------------------------------------------
> > > > This SF.Net email is sponsored by: InterSystems CACHE
> > > > FREE OODBMS DOWNLOAD - A multidimensional database that combines
> > > > robust object and relational technologies, making it a perfect match
> > > > for Java, C++,COM, XML, ODBC and JDBC. www.intersystems.com/match8
> > > > _______________________________________________
> > > > Xen-devel mailing list
> > > > Xen-devel@lists.sourceforge.net
> > > > https://lists.sourceforge.net/lists/listinfo/xen-devel
> > > >
> >
> >



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Any other possible solutions?


-Kip


On Tue, 16 Nov 2004, Keir Fraser wrote:

>
> Ah yes, if VMs use PSE then we were plannign to abuse PAT to provide
> some protection for us. However, VMs can *not* currently use PSE at
> the moment and, even if they could, we have since discovered that our
> abuse of PAT would not work anyway. :-)
>
> -- Keir
>
> >
> > I was told there were security issues with allowing PSE in VMs outright.
> >
> > -Kip
> >
> > >
> > > The two features are completely unrelated.
> > >
> > > -- Keir
> > >
> > > > My understanding was that PAT would likely be used to allow VMs to use
> > > > PSE, is that not correct?
> > > >
> > > > -Kip
> > > >
> > > > > > We don't use SYSCALL/SYSENTER, PAT or VME.
> > > > >
> > > > > ah, good.
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > -------------------------------------------------------
> > > > > This SF.Net email is sponsored by: InterSystems CACHE
> > > > > FREE OODBMS DOWNLOAD - A multidimensional database that combines
> > > > > robust object and relational technologies, making it a perfect match
> > > > > for Java, C++,COM, XML, ODBC and JDBC. www.intersystems.com/match8
> > > > > _______________________________________________
> > > > > Xen-devel mailing list
> > > > > Xen-devel@lists.sourceforge.net
> > > > > https://lists.sourceforge.net/lists/listinfo/xen-devel
> > > > >
> > >
> > >
>
>
>
> -------------------------------------------------------
> This SF.Net email is sponsored by: InterSystems CACHE
> FREE OODBMS DOWNLOAD - A multidimensional database that combines
> robust object and relational technologies, making it a perfect match
> for Java, C++,COM, XML, ODBC and JDBC. www.intersystems.com/match8
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/xen-devel
>


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Oh yes. It's only a problem for SMP guests anyway (which are making
excellent progress but not ready for check-in yet). Since we currently
just enclose any suspect code in Xen with a "big fat domain lock"
right now, we couldn't have any problem as only one "virtual cpu" can
update pagetables at any point in time. The PAT trick was looking
forward to the possibility that we could allow vcpus to go at their
pagetables with no locking in Xen required. That now won't be
possible, but I expect that isn't a problem. I just like lock-free
code, is all. :-)

-- Keir

> Any other possible solutions?
>
>
> -Kip
>
>
> On Tue, 16 Nov 2004, Keir Fraser wrote:
>
> >
> > Ah yes, if VMs use PSE then we were plannign to abuse PAT to provide
> > some protection for us. However, VMs can *not* currently use PSE at
> > the moment and, even if they could, we have since discovered that our
> > abuse of PAT would not work anyway. :-)
> >
> > -- Keir
> >
> > >
> > > I was told there were security issues with allowing PSE in VMs outright.
> > >
> > > -Kip
> > >
> > > >
> > > > The two features are completely unrelated.
> > > >
> > > > -- Keir
> > > >
> > > > > My understanding was that PAT would likely be used to allow VMs to use
> > > > > PSE, is that not correct?
> > > > >
> > > > > -Kip
> > > > >
> > > > > > > We don't use SYSCALL/SYSENTER, PAT or VME.
> > > > > >
> > > > > > ah, good.
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > > -------------------------------------------------------
> > > > > > This SF.Net email is sponsored by: InterSystems CACHE
> > > > > > FREE OODBMS DOWNLOAD - A multidimensional database that combines
> > > > > > robust object and relational technologies, making it a perfect match
> > > > > > for Java, C++,COM, XML, ODBC and JDBC. www.intersystems.com/match8
> > > > > > _______________________________________________
> > > > > > Xen-devel mailing list
> > > > > > Xen-devel@lists.sourceforge.net
> > > > > > https://lists.sourceforge.net/lists/listinfo/xen-devel
> > > > > >
> > > >
> > > >
> >
> >
> >
> > -------------------------------------------------------
> > This SF.Net email is sponsored by: InterSystems CACHE
> > FREE OODBMS DOWNLOAD - A multidimensional database that combines
> > robust object and relational technologies, making it a perfect match
> > for Java, C++,COM, XML, ODBC and JDBC. www.intersystems.com/match8
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/xen-devel
> >



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