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From Anthony Xu <Xuefei...@citrix.com>
Subject RE: CentOS System Offering Thread
Date Thu, 13 Dec 2012 18:29:07 GMT
32-bit PV might have better performance than 64-bit PV on XEN, 
In 64 bit mode, there are only ring 0 and ring 3, both Guest OS and guest application are
running on ring3 , application system call needs to be trapped into hypervisor and then be
injected into guest OS.
In 32 bit mode, there are ring 0, 1, 2, 3.   Guest OS is running on ring 1, application is
running on ring 3, hypervisor doesn't need to trap system call.

That might be one of reasons dom0 is 32 bit in XenServer/XCP.

Anthony

> -----Original Message-----
> From: Donal Lafferty [mailto:donal.lafferty@citrix.com]
> Sent: Thursday, December 13, 2012 10:20 AM
> To: cloudstack-dev@incubator.apache.org
> Subject: RE: CentOS System Offering Thread
> 
> The choice of 32-bit OS may be to support legacy servers, but I really
> don't know.
> 
> 
> -----Original Message-----
> From: Musayev, Ilya [mailto:imusayev@webmd.net]
> Sent: 13 December 2012 4:50 PM
> To: cloudstack-dev@incubator.apache.org
> Subject: RE: CentOS System Offering Thread
> 
> I did.. reviewed buildsystemvm.sh script - seems self-explanatory.
> 
> There are 2 major parts to this task as I see it.
> 
> Part1
> System Image Side:
> We  need to alter the "debootsrap" to "mock" and change debian specific
> configs to redhat.  Once functional - I need to create 3 versions of
> the template for VmWare, Xen and KVM. I have VmWare in house - no
> Xen/KVM yet - we can deal with this - once I get there.
> 
> Part2
> Systemvm.iso will need to be updated and include rhel version of the
> patch scripts we run on power on.
> 
> 
> What is the reason for running 32bit OS vs 64? Are we open to changing
> that to 64bit - which would probably benefit very large implementations
> using basic zones. Or should we keep it 32 bit for consistency reason?
> 
> -----Original Message-----
> From: Donal Lafferty [mailto:donal.lafferty@citrix.com]
> Sent: Thursday, December 13, 2012 7:47 AM
> To: cloudstack-dev@incubator.apache.org
> Subject: RE: CentOS System Offering Thread
> 
> WRT to CentOS.  Did you survey the changes required?
> 
> Would be great to have these on a wiki page for future reference and
> history tracking.
> 
> 
> DL
> 
> 
> -----Original Message-----
> From: Musayev, Ilya [mailto:imusayev@webmd.net]
> Sent: 12 December 2012 9:33 PM
> To: cloudstack-dev@incubator.apache.org
> Subject: RE: CentOS System Offering Thread
> 
> Donal
> 
> See response in line..
> 
> >> 1.  Can you remind me of the download link for the Wheezy systemVM?
> I've only seen Squeeze.
> 
> I confused the names - I think - its squeeze - wheezy is the latest
> offering with 3.x kernel. I guess by now you noticed I'm not debian
> user :)
> 
> >> 2.  In addition to a Debian system VM, I'd like to see one and only
> one CentOS VM in addition to Debian.  I get the impression that CentOS
> has a different and desirable licensing regime, but do correct me if
> I'm wrong.
> 
> I'm under impression CentOS has very liberal licensing structure. I
> don't believe we should have an issue here - but I'm by no means a
> licensing expert.
> 
> I think it's reasonable to have 1 other offering only..
> 
> Thanks
> ilya
> 
> 
> -----Original Message-----
> From: Donal Lafferty [mailto:donal.lafferty@citrix.com]
> Sent: Wednesday, December 12, 2012 3:34 PM
> To: cloudstack-dev@incubator.apache.org
> Subject: RE: CentOS System Offering Thread
> 
> 1.  Can you remind me of the download link for the Wheezy systemVM?
> I've only seen Squeeze.
> 
> 2.  In addition to a Debian system VM, I'd like to see one and only one
> CentOS VM in addition to Debian.  I get the impression that CentOS has
> a different and desirable licensing regime, but do correct me if I'm
> wrong.
> 
> DL
> 
> -----Original Message-----
> From: Musayev, Ilya [mailto:imusayev@webmd.net]
> Sent: 12 December 2012 8:06 PM
> To: cloudstack-dev@incubator.apache.org
> Subject: RE: CentOS System Offering Thread
> 
> Joe
> 
> Your point is clear and well taken. Nobody wants to be in business of
> maintaining myriad of distros out there for something that should not
> be changed anyway.
> 
> I see two solutions then:
> 
> 1) update the existing debian wheezy image to reflect latest fixes -
> which is probably something that should do anyway.
> 
> 2) maybe have a section of  - "user submitted and unsupported" system
> offerings? We can clearly state - we support 1 type of offering and
> other offerings are optional and unsupported  - but your own
> responsibility and should be used by advanced users only.
> 
> Thoughts?
> 
> Regards
> -ilya
> 
> -----Original Message-----
> From: Joe Brockmeier [mailto:jzb@zonker.net]
> Sent: Wednesday, December 12, 2012 11:02 AM
> To: cloudstack-dev@incubator.apache.org
> Subject: Re: CentOS System Offering Thread
> 
> On Tue, Dec 11, 2012, at 11:32 PM, Marcus Sorensen wrote:
> > This is pretty important.  Anyone should be able to roll their own,
> > rather than relying on a single potentially out-of-date image. It
> > seems like it would be pretty simple and straightforward on the face
> > of it, however many of the scripts have been written specifically for
> > Debian. I'd honestly be ok with having to stick to a particular
> distro
> > if I at least had clear instructions on how to make my own, I
> > understand the need to program against a single defined userspace.
> 
> I see a potential problem with this.
> 
> Any scenario where users are customizing part of the stack means
> additional variables which means additional problems. If we target
> Debian, trying to create a system VM from CentOS/RHEL means different
> libraries, etc. - which means a number of potential problems cropping
> up where there were none before.
> 
> I'm not saying users *shouldn't* be able to do this - just that I
> haven't noticed anyone raising the issue that we'll probably start
> seeing a fair number more bugs if replacing the system VM becomes a
> standard practice. There's a reason, for instance, that Linux vendors
> don't support custom kernels - and what's being proposed here is
> swapping out an entire OS.
> 
> It's going to make things a bit more tricky when someone reports a bug
> and they're using a roll-your-own system VM and the people doing the
> testing are using a different one.
> 
> Again - not saying we shouldn't do this, but I'd like to see that given
> a bit more consideration when we're discussing the issue.
> 
> Best,
> 
> jzb
> --
> Joe Brockmeier
> jzb@zonker.net
> Twitter: @jzb
> http://www.dissociatedpress.net/
> 
> 
> 
> 
> 


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