Xen 4.3: x86 32 bit code removed or depreciated?

Xen 4.3: x86 32 bit code removed or depreciated?

[Ian Murray]

Hi,

I have seen in various places that x86 32 bit support would be dropped for 4.3 and the only mention in the release material is a one-liner in the "Xen 4.3 Feature List" in the wiki

	* Remove 32-bit and ia64 
I know a lot of code was removed for ia64 because there are comments to the effect in the commit statistics, but no mention of 32-bit/x86.

Has the code been actively removed, or is still there but depreciated?

Thanks in advance,

Ian.

Re: Xen 4.3: x86 32 bit code removed or depreciated?

[Jan Beulich]

>>> On 10.07.13 at 12:23, Ian Murray <murrayie@yahoo.co.uk> wrote:
> I have seen in various places that x86 32 bit support would be dropped for 
> 4.3 and the only mention in the release material is a one-liner in the "Xen 
> 4.3 Feature List" in the wiki
> 
> 	* Remove 32-bit and ia64 
> I know a lot of code was removed for ia64 because there are comments to the 
> effect in the commit statistics, but no mention of 32-bit/x86.
> 
> Has the code been actively removed, or is still there but depreciated?

I'm sorry, but why do you ask here rather than checking the sources
(xen/arch/x86/x86_32/ is gone, just to name a simple and obvious
example) or the commit log (5d1181a5 "xen: Remove x86_32 build
target." is pretty explicit I would think).

Jan

Re: Xen 4.3: x86 32 bit code removed or depreciated?

[Matthew Daley]

FWIW, it shows that x86 32-bit is still supported on
http://wiki.xenproject.org/wiki/Xen_Release_Features . (Release date
is incorrect too.)

I'd edit it myself, but have no account handy.

Re: Xen 4.3: x86 32 bit code removed or depreciated?

[George Dunlap]

On Wed, Jul 10, 2013 at 12:08 PM, Matthew Daley <mattjd@gmail.com> wrote:
> FWIW, it shows that x86 32-bit is still supported on
> http://wiki.xenproject.org/wiki/Xen_Release_Features . (Release date
> is incorrect too.)
>
> I'd edit it myself, but have no account handy.

Thanks for pointing that out -- I just fixed it.

 -George

Re: Xen 4.3: x86 32 bit code removed or depreciated?

[George Dunlap]

On Wed, Jul 10, 2013 at 11:34 AM, Jan Beulich <JBeulich@suse.com> wrote:
>>>> On 10.07.13 at 12:23, Ian Murray <murrayie@yahoo.co.uk> wrote:
>> I have seen in various places that x86 32 bit support would be dropped for
>> 4.3 and the only mention in the release material is a one-liner in the "Xen
>> 4.3 Feature List" in the wiki
>>
>>       * Remove 32-bit and ia64
>> I know a lot of code was removed for ia64 because there are comments to the
>> effect in the commit statistics, but no mention of 32-bit/x86.
>>
>> Has the code been actively removed, or is still there but depreciated?
>
> I'm sorry, but why do you ask here rather than checking the sources
> (xen/arch/x86/x86_32/ is gone, just to name a simple and obvious
> example) or the commit log (5d1181a5 "xen: Remove x86_32 build
> target." is pretty explicit I would think).

Just to be clear, this is the 32-bit *hypervisor* which was removed.
32-bit tools in a 32-bit dom0 still work.

 -George

Re: Xen 4.3: x86 32 bit code removed or depreciated?

[Ian Murray]

----- Original Message -----
> From: George Dunlap <dunlapg@umich.edu>
> To: Jan Beulich <JBeulich@suse.com>
> Cc: Ian Murray <murrayie@yahoo.co.uk>; xen-devel <xen-devel@lists.xen.org>
> Sent: Wednesday, 10 July 2013, 12:10
> Subject: Re: [Xen-devel] Xen 4.3: x86 32 bit code removed or depreciated?
> 
> On Wed, Jul 10, 2013 at 11:34 AM, Jan Beulich <JBeulich@suse.com> wrote:
>>>>>  On 10.07.13 at 12:23, Ian Murray <murrayie@yahoo.co.uk> 
> wrote:
>>>  I have seen in various places that x86 32 bit support would be dropped 
> for
>>>  4.3 and the only mention in the release material is a one-liner in the 
> "Xen
>>>  4.3 Feature List" in the wiki
>>> 
>>>        * Remove 32-bit and ia64
>>>  I know a lot of code was removed for ia64 because there are comments to 
> the
>>>  effect in the commit statistics, but no mention of 32-bit/x86.
>>> 
>>>  Has the code been actively removed, or is still there but depreciated?
>> 
>>  I'm sorry, but why do you ask here rather than checking the sources
>>  (xen/arch/x86/x86_32/ is gone, just to name a simple and obvious
>>  example) or the commit log (5d1181a5 "xen: Remove x86_32 build
>>  target." is pretty explicit I would think).
> 
> Just to be clear, this is the 32-bit *hypervisor* which was removed.
> 32-bit tools in a 32-bit dom0 still work.
> 

Thanks. Thanks for clearing that up. Perhaps off-topic for dev, but are there any advantages to running a 32 bit dom0 as in this configuration?


> -George
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel
> 

Re: Xen 4.3: x86 32 bit code removed or depreciated?

[George Dunlap]

On Wed, Jul 10, 2013 at 12:28 PM, Ian Murray <murrayie@yahoo.co.uk> wrote:

>> Just to be clear, this is the 32-bit *hypervisor* which was removed.
>> 32-bit tools in a 32-bit dom0 still work.
>>
>
> Thanks. Thanks for clearing that up. Perhaps off-topic for dev, but are there any advantages to running a 32 bit dom0 as in this configuration?

Probably the biggest thing is about performance.  Until the PVH mode
is implemented, 64-bit PV guests will have a performance degradation,
due to the way the architecture changed between 32-bit and 64-bit.
The reason is quite technical, but you can read a summary of it here:

http://blog.xen.org/index.php/2012/10/31/the-paravirtualization-spectrum-part-2-from-poles-to-a-spectrum/

 -George

Re: Xen 4.3: x86 32 bit code removed or depreciated?

[David Vrabel]

On 10/07/13 12:32, George Dunlap wrote:
> On Wed, Jul 10, 2013 at 12:28 PM, Ian Murray <murrayie@yahoo.co.uk> wrote:
> 
>>> Just to be clear, this is the 32-bit *hypervisor* which was removed.
>>> 32-bit tools in a 32-bit dom0 still work.
>>>
>>
>> Thanks. Thanks for clearing that up. Perhaps off-topic for dev, but are there any advantages to running a 32 bit dom0 as in this configuration?
> 
> Probably the biggest thing is about performance.  Until the PVH mode
> is implemented, 64-bit PV guests will have a performance degradation,
> due to the way the architecture changed between 32-bit and 64-bit.

This isn't really that true for real dom0 workloads.

Most of the theoretical performance penalty caused by system calls
having to trap into the hypervisor are offset by the general performance
improvement of the amd64 archiecture (e.g., more general purpose
registers and the lack of high memory needing bouncing/mapping all the
time).

David

Re: Xen 4.3: x86 32 bit code removed or depreciated?

[Ian Murray]

----- Original Message -----
> From: George Dunlap <George.Dunlap@eu.citrix.com>
> To: Ian Murray <murrayie@yahoo.co.uk>
> Cc: Jan Beulich <JBeulich@suse.com>; xen-devel <xen-devel@lists.xen.org>
> Sent: Wednesday, 10 July 2013, 12:32
> Subject: Re: [Xen-devel] Xen 4.3: x86 32 bit code removed or depreciated?
> 
> On Wed, Jul 10, 2013 at 12:28 PM, Ian Murray <murrayie@yahoo.co.uk> wrote:
> 
>>>  Just to be clear, this is the 32-bit *hypervisor* which was removed.
>>>  32-bit tools in a 32-bit dom0 still work.
>>> 
>> 
>>  Thanks. Thanks for clearing that up. Perhaps off-topic for dev, but are 
> there any advantages to running a 32 bit dom0 as in this configuration?
> 
> Probably the biggest thing is about performance.  Until the PVH mode
> is implemented, 64-bit PV guests will have a performance degradation,
> due to the way the architecture changed between 32-bit and 64-bit.
> The reason is quite technical, but you can read a summary of it here:
> 
> http://blog.xen.org/index.php/2012/10/31/the-paravirtualization-spectrum-part-2-from-poles-to-a-spectrum/
> 
> -George

Thanks. I was alluding to this when I asked. I have looked at the blog post before when trying to understand what PVH was. I will give it a proper read. Hopefully I can follow enough of it.

Thanks again.


> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel
> 

Re: Xen 4.3: x86 32 bit code removed or depreciated?

[Ian Murray]

----- Original Message -----
> From: Jan Beulich <JBeulich@suse.com>
> To: Ian Murray <murrayie@yahoo.co.uk>
> Cc: xen-devel <xen-devel@lists.xen.org>
> Sent: Wednesday, 10 July 2013, 11:34
> Subject: Re: [Xen-devel] Xen 4.3: x86 32 bit code removed or
 depreciated?
> 
>>>>  On 10.07.13 at 12:23, Ian Murray <murrayie@yahoo.co.uk> 
> wrote:
>>  I have seen in various places that x86 32 bit support would be dropped for 
>>  4.3 and the only mention in the release material is a one-liner in the 
> "Xen 
>>  4.3 Feature List" in the wiki
>> 
>>      * Remove 32-bit and ia64 
>>  I know a lot of code was removed for ia64 because there are comments to the 
> 
>>  effect in the commit statistics, but no mention of 32-bit/x86.
>> 
>>  Has the code been actively removed, or is still there but depreciated?
> 
> I'm sorry, but why do you ask here rather than checking the sources
> (xen/arch/x86/x86_32/ is gone, just to name a simple and obvious
> example) or the commit log (5d1181a5 "xen: Remove x86_32 build
> target." is pretty explicit I would think).

Apology accepted. :)

You assume that I am fully familiar with the source layout to know what is missing and that I possess more than rudimentary git skills or am experienced enough to know the exact search terms that would yield results. Well, I am not and I don't.

Yes, I could have discovered this myself, but it would have taken me some time to arrive at a definitive answer (as I am no expert) and I thought it quicker and not too onerous on other people to ask the list; Sorry, if that wasn't the case for you. You didn't have to "waste" your time answering me and I am sure it took more time to back up your complaint than a simple "yes" or "no", but thanks for the answer to my question. I do appreciate it. Unfortunately, nobody pays me to sit and look at Xen source code, so I have to do it outside of my day job.

Of course, I did look in the release notes which is where it *should be* but IMHO those release notes look more like marketing spiel than anything useful technically.

> 
> Jan
> 

Re: Xen 4.3: x86 32 bit code removed or depreciated?

[George Dunlap]

On Wed, Jul 10, 2013 at 12:18 PM, Ian Murray <murrayie@yahoo.co.uk> wrote:
>
>
>
>
> ----- Original Message -----
>> From: Jan Beulich <JBeulich@suse.com>
>> To: Ian Murray <murrayie@yahoo.co.uk>
>> Cc: xen-devel <xen-devel@lists.xen.org>
>> Sent: Wednesday, 10 July 2013, 11:34
>> Subject: Re: [Xen-devel] Xen 4.3: x86 32 bit code removed or
>  depreciated?
>>
>>>>>  On 10.07.13 at 12:23, Ian Murray <murrayie@yahoo.co.uk>
>> wrote:
>>>  I have seen in various places that x86 32 bit support would be dropped for
>>>  4.3 and the only mention in the release material is a one-liner in the
>> "Xen
>>>  4.3 Feature List" in the wiki
>>>
>>>      * Remove 32-bit and ia64
>>>  I know a lot of code was removed for ia64 because there are comments to the
>>
>>>  effect in the commit statistics, but no mention of 32-bit/x86.
>>>
>>>  Has the code been actively removed, or is still there but depreciated?
>>
>> I'm sorry, but why do you ask here rather than checking the sources
>> (xen/arch/x86/x86_32/ is gone, just to name a simple and obvious
>> example) or the commit log (5d1181a5 "xen: Remove x86_32 build
>> target." is pretty explicit I would think).
>
> Apology accepted. :)
>
> You assume that I am fully familiar with the source layout to know what is missing and that I possess more than rudimentary git skills or am experienced enough to know the exact search terms that would yield results. Well, I am not and I don't.
>
> Yes, I could have discovered this myself, but it would have taken me some time to arrive at a definitive answer (as I am no expert) and I thought it quicker and not too onerous on other people to ask the list; Sorry, if that wasn't the case for you. You didn't have to "waste" your time answering me and I am sure it took more time to back up your complaint than a simple "yes" or "no", but thanks for the answer to my question. I do appreciate it. Unfortunately, nobody pays me to sit and look at Xen source code, so I have to do it outside of my day job.
>
> Of course, I did look in the release notes which is where it *should be* but IMHO those release notes look more like marketing spiel than anything useful technically.

I think that's a bit unfair.  The release notes page is 1/3 new
features, 1/3 comment on the change to installing in /usr/local/ by
default (technical) and 1/3 known issues, which are also very
technical in nature.  Even the new features contain a lot of
techinical links: how to switch to the old qemu if you have problems,
how to use the new multiple USB device feature, and links to how to
set up openvswitch on your system.

I just added a comment about removing 32-bit x86 and ia64 code.  If
you have other suggestions for what would be useful to include, feel
free to suggest it.

 -George

Re: Xen 4.3: x86 32 bit code removed or depreciated?

[Ian Murray]

----- Original Message -----
> From: George Dunlap <George.Dunlap@eu.citrix.com>
> To: Ian Murray <murrayie@yahoo.co.uk>
> Cc: Jan Beulich <JBeulich@suse.com>; xen-devel <xen-devel@lists.xen.org>
> Sent: Wednesday, 10 July 2013, 12:28
> Subject: Re: [Xen-devel] Xen 4.3: x86 32 bit code removed or depreciated?
> 
> On Wed, Jul 10, 2013 at 12:18 PM, Ian Murray <murrayie@yahoo.co.uk> wrote:
>> 
>> 
>> 
>> 
>>  ----- Original Message -----
>>>  From: Jan Beulich <JBeulich@suse.com>
>>>  To: Ian Murray <murrayie@yahoo.co.uk>
>>>  Cc: xen-devel <xen-devel@lists.xen.org>
>>>  Sent: Wednesday, 10 July 2013, 11:34
>>>  Subject: Re: [Xen-devel] Xen 4.3: x86 32 bit code removed or
>>   depreciated?
>>> 
>>>>>>   On 10.07.13 at 12:23, Ian Murray 
> <murrayie@yahoo.co.uk>
>>>  wrote:
>>>>   I have seen in various places that x86 32 bit support would be 
> dropped for
>>>>   4.3 and the only mention in the release material is a one-liner in 
> the
>>>  "Xen
>>>>   4.3 Feature List" in the wiki
>>>> 
>>>>       * Remove 32-bit and ia64
>>>>   I know a lot of code was removed for ia64 because there are 
> comments to the
>>> 
>>>>   effect in the commit statistics, but no mention of 32-bit/x86.
>>>> 
>>>>   Has the code been actively removed, or is still there but 
> depreciated?
>>> 
>>>  I'm sorry, but why do you ask here rather than checking the sources
>>>  (xen/arch/x86/x86_32/ is gone, just to name a simple and obvious
>>>  example) or the commit log (5d1181a5 "xen: Remove x86_32 build
>>>  target." is pretty explicit I would think).
>> 
>>  Apology accepted. :)
>> 
>>  You assume that I am fully familiar with the source layout to know what is 
> missing and that I possess more than rudimentary git skills or am experienced 
> enough to know the exact search terms that would yield results. Well, I am not 
> and I don't.
>> 
>>  Yes, I could have discovered this myself, but it would have taken me some 
> time to arrive at a definitive answer (as I am no expert) and I thought it 
> quicker and not too onerous on other people to ask the list; Sorry, if that 
> wasn't the case for you. You didn't have to "waste" your time 
> answering me and I am sure it took more time to back up your complaint than a 
> simple "yes" or "no", but thanks for the answer to my 
> question. I do appreciate it. Unfortunately, nobody pays me to sit and look at 
> Xen source code, so I have to do it outside of my day job.
>> 
>>  Of course, I did look in the release notes which is where it *should be* 
> but IMHO those release notes look more like marketing spiel than anything useful 
> technically.
> 
> I think that's a bit unfair.  The release notes page is 1/3 new
> features, 1/3 comment on the change to installing in /usr/local/ by
> default (technical) and 1/3 known issues, which are also very
> technical in nature.  Even the new features contain a lot of
> techinical links: how to switch to the old qemu if you have problems,
> how to use the new multiple USB device feature, and links to how to
> set up openvswitch on your system.

Yes, it probably was a bit unfair. Sorry. I was in a bad mood by that point and it was a bit off-the-cuff. ;) It's probably because a few media sites have been quoting it verbatim, rather actual content

I wasn't subscribed when the 32 bit announcement was made back in the day and only learned about it in the The Register article announcing the 4.3 release. Normally that means the opposite is true :) (They managed to mis-spell your name even).


> 
> I just added a comment about removing 32-bit x86 and ia64 code.  If
> you have other suggestions for what would be useful to include, feel
> free to suggest it.
> 
> -George
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel
> 

Re: Xen 4.3: x86 32 bit code removed or depreciated?

[George Dunlap]

On 10/07/13 14:04, Ian Murray wrote:
>
>
>
> ----- Original Message -----
>> From: George Dunlap <George.Dunlap@eu.citrix.com>
>> To: Ian Murray <murrayie@yahoo.co.uk>
>> Cc: Jan Beulich <JBeulich@suse.com>; xen-devel <xen-devel@lists.xen.org>
>> Sent: Wednesday, 10 July 2013, 12:28
>> Subject: Re: [Xen-devel] Xen 4.3: x86 32 bit code removed or depreciated?
>>
>> On Wed, Jul 10, 2013 at 12:18 PM, Ian Murray <murrayie@yahoo.co.uk> wrote:
>>>
>>>
>>>
>>>   ----- Original Message -----
>>>>   From: Jan Beulich <JBeulich@suse.com>
>>>>   To: Ian Murray <murrayie@yahoo.co.uk>
>>>>   Cc: xen-devel <xen-devel@lists.xen.org>
>>>>   Sent: Wednesday, 10 July 2013, 11:34
>>>>   Subject: Re: [Xen-devel] Xen 4.3: x86 32 bit code removed or
>>>    depreciated?
>>>>>>>    On 10.07.13 at 12:23, Ian Murray
>> <murrayie@yahoo.co.uk>
>>>>   wrote:
>>>>>    I have seen in various places that x86 32 bit support would be
>> dropped for
>>>>>    4.3 and the only mention in the release material is a one-liner in
>> the
>>>>   "Xen
>>>>>    4.3 Feature List" in the wiki
>>>>>
>>>>>        * Remove 32-bit and ia64
>>>>>    I know a lot of code was removed for ia64 because there are
>> comments to the
>>>>>    effect in the commit statistics, but no mention of 32-bit/x86.
>>>>>
>>>>>    Has the code been actively removed, or is still there but
>> depreciated?
>>>>   I'm sorry, but why do you ask here rather than checking the sources
>>>>   (xen/arch/x86/x86_32/ is gone, just to name a simple and obvious
>>>>   example) or the commit log (5d1181a5 "xen: Remove x86_32 build
>>>>   target." is pretty explicit I would think).
>>>   Apology accepted. :)
>>>
>>>   You assume that I am fully familiar with the source layout to know what is
>> missing and that I possess more than rudimentary git skills or am experienced
>> enough to know the exact search terms that would yield results. Well, I am not
>> and I don't.
>>>   Yes, I could have discovered this myself, but it would have taken me some
>> time to arrive at a definitive answer (as I am no expert) and I thought it
>> quicker and not too onerous on other people to ask the list; Sorry, if that
>> wasn't the case for you. You didn't have to "waste" your time
>> answering me and I am sure it took more time to back up your complaint than a
>> simple "yes" or "no", but thanks for the answer to my
>> question. I do appreciate it. Unfortunately, nobody pays me to sit and look at
>> Xen source code, so I have to do it outside of my day job.
>>>   Of course, I did look in the release notes which is where it *should be*
>> but IMHO those release notes look more like marketing spiel than anything useful
>> technically.
>>
>> I think that's a bit unfair.  The release notes page is 1/3 new
>> features, 1/3 comment on the change to installing in /usr/local/ by
>> default (technical) and 1/3 known issues, which are also very
>> technical in nature.  Even the new features contain a lot of
>> techinical links: how to switch to the old qemu if you have problems,
>> how to use the new multiple USB device feature, and links to how to
>> set up openvswitch on your system.
> Yes, it probably was a bit unfair. Sorry. I was in a bad mood by that point and it was a bit off-the-cuff. ;) It's probably because a few media sites have been quoting it verbatim, rather actual content

Reporters are pretty lazy. :-)  If you make an announcement and write it 
in the form of the article you want published, many news outlets will 
just take what you wrote and publish it unchanged.  One of the reasons 
for having the release notes be part marketing is so that we can 
influence what people say in the announcements.  If it's ready to be 
quoted, then reporters will often just copy it or quote it verbatim; but 
if it's not, then who knows what they'll come up with (if they say 
anything at all).

Obviously there's a balance to be struck there, but I think we didn't do 
too badly.

  -George

Re: Xen 4.3: x86 32 bit code removed or depreciated?

[Pasi Kärkkäinen]

On Wed, Jul 10, 2013 at 12:28:18PM +0100, George Dunlap wrote:
> >
> > Of course, I did look in the release notes which is where it *should be* but IMHO those release notes look more like marketing spiel than anything useful technically.
> 
> I think that's a bit unfair.  The release notes page is 1/3 new
> features, 1/3 comment on the change to installing in /usr/local/ by
> default (technical) and 1/3 known issues, which are also very
> technical in nature.  Even the new features contain a lot of
> techinical links: how to switch to the old qemu if you have problems,
> how to use the new multiple USB device feature, and links to how to
> set up openvswitch on your system.
> 
> I just added a comment about removing 32-bit x86 and ia64 code.  If
> you have other suggestions for what would be useful to include, feel
> free to suggest it.
> 

I modified the wiki pages a bit aswell, and tried clarifying it's the host/hypervisor supported that has been removed, and 32bit VMs are still supported.

Should we have an explicit line for that on: http://wiki.xen.org/wiki/Xen_Release_Features ? 

Someone might still read the current host info as "support for 32bit VMs has been removed" .. which obviously isn't true. 

-- Pasi