From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Heinsius Subject: assembly-language mutex support Date: Fri, 04 Apr 2008 22:45:21 +0200 Message-ID: <47F69361.7040603@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org Hi, I read some time ago that Xen does not have assembly-language mutex support. Is this still the case in Xen 3.2? best regards, Bart. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: assembly-language mutex support Date: Fri, 04 Apr 2008 22:23:06 +0100 Message-ID: References: <47F69361.7040603@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <47F69361.7040603@gmail.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Bart Heinsius , xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org What does that even mean? -- Keir On 4/4/08 21:45, "Bart Heinsius" wrote: > Hi, > > I read some time ago that Xen does not have assembly-language mutex support. > Is this still the case in Xen 3.2? > > best regards, > Bart. > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Heinsius Subject: Re: assembly-language mutex support Date: Fri, 04 Apr 2008 23:30:42 +0200 Message-ID: <47F69E02.9040403@gmail.com> References: Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0395329829==" Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Mime-version: 1.0 Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Keir Fraser Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org --===============0395329829== Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit I don't know what it means exactly, except that it hear it can cause problems for BDB.
I want to run a production Zimbra instance in a Xen vm and certain people at Zimbra advice me to not do that unless it has assembly-language mutex support, since BDB uses assembly level mutex locks by default.
I was pointed to:

https://bugzilla.redhat.com/show_bug.cgi?id=91933
http://www.openldap.org/lists/openldap-software/200603/msg00214.html

and
http://www.zimbra.com/forums/installation/14121-virtualization-zimbra.html

-- Bart

Keir Fraser wrote:

What does that even mean?

 -- Keir


On 4/4/08 21:45, "Bart Heinsius" <bheinsius@gmail.com> wrote:

Hi,

I read some time ago that Xen does not have assembly-language mutex support.
Is this still the case in Xen 3.2?

best regards,
Bart.


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel

--===============0395329829== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel --===============0395329829==-- From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: assembly-language mutex support Date: Sat, 05 Apr 2008 10:04:12 +0100 Message-ID: References: <47F69E02.9040403@gmail.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1866299738==" Return-path: In-Reply-To: <47F69E02.9040403@gmail.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Mime-version: 1.0 Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Bart Heinsius Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org > This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. --===============1866299738== Content-type: multipart/alternative; boundary="B_3290234657_22397944" > This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. --B_3290234657_22397944 Content-type: text/plain; charset="ISO-8859-1" Content-transfer-encoding: quoted-printable Ah, I think this is related to difficulties supporting =8Cnegative segment accesses=B9. This means we have to rebuild glibc and we lose some NPTL functionality in doing that. However, this problem is not present if you run a 64-bit hypervisor. You ca= n run 64-bit or 32-bit (PAE) Linux guests on the 64-bit hypervisor with no limitations (even as domain 0) and the =8Cnegative segment access=B9 problem goes away. You should try that out! The only tricky point may be if the distro you use has deliberately picked different glibc when running a 32-bit Xen version o= f Linux, despite the fact you are running on 64-bit hypervisor. In that case you might have to tweak a ld.so config file to stop searching for nosegneg libraries. But short answer is: use a 64-bit hypervisor and it should all work fine. -- Keir On 4/4/08 22:30, "Bart Heinsius" wrote: > I don't know what it means exactly, except that it hear it can cause prob= lems > for BDB. > I want to run a production Zimbra instance in a Xen vm and certain people= at > Zimbra advice me to not do that unless it has assembly-language mutex sup= port, > since BDB uses assembly level mutex locks by default. > I was pointed to: > https://bugzilla.redhat.com/show_bug.cgi?id=3D91933 > http://www.openldap.org/lists/openldap-software/200603/msg00214.html >=20 > and > http://www.zimbra.com/forums/installation/14121-virtualization-zimbra.htm= l >=20 > -- Bart >=20 > Keir Fraser wrote: >> =20 >> What does that even mean? >>=20 >> -- Keir >>=20 >>=20 >> On 4/4/08 21:45, "Bart Heinsius" >> wrote: >>=20 >> =20 >> =20 >>> =20 >>> Hi, >>>=20 >>> I read some time ago that Xen does not have assembly-language mutex sup= port. >>> Is this still the case in Xen 3.2? >>>=20 >>> best regards, >>> Bart. >>>=20 >>>=20 >>> _______________________________________________ >>> Xen-devel mailing list >>> Xen-devel@lists.xensource.com >>> http://lists.xensource.com/xen-devel >>> =20 >>> =20 >> =20 >>=20 >>=20 >> =20 >=20 >=20 >=20 > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel --B_3290234657_22397944 Content-type: text/html; charset="ISO-8859-1" Content-transfer-encoding: quoted-printable Re: [Xen-devel] assembly-language mutex support Ah, I= think this is related to difficulties supporting ‘negative segment ac= cesses’. This means we have to rebuild glibc and we lose some NPTL fun= ctionality in doing that.

However, this problem is not present if you run a 64-bit hypervisor. You ca= n run 64-bit or 32-bit (PAE) Linux guests on the 64-bit hypervisor with no l= imitations (even as domain 0) and the ‘negative segment access’ = problem goes away.

You should try that out! The only tricky point may be if the distro you use= has deliberately picked different glibc when running a 32-bit Xen version o= f Linux, despite the fact you are running on 64-bit hypervisor. In tha= t case you might have to tweak a ld.so config file to stop searching for nos= egneg libraries.

But short answer is: use a 64-bit hypervisor and it should all work fine.
-- Keir

On 4/4/08 22:30, "Bart Heinsius" <bheinsius@gmail.com> wrot= e:

I don't know what it means exactly, except that it hear= it can cause problems for BDB.
I want to run a production Zimbra instance in a Xen vm and certain people a= t Zimbra advice me to not do that unless it has assembly-language mutex supp= ort, since BDB uses assembly level mutex locks by default.
I was pointed to:
https://bugzilla.redhat.com/show_bug.cgi?id=3D91933
http://www.openldap.org/lists/openldap-software/200603/msg00214.html=

and
http://www.zimbra.com/forums/installation/14121-virtualization-zim= bra.html

-- Bart

Keir Fraser wrote:

What does that even mean?

-- Keir

On 4/4/08 21:45, "Bart Heinsius" <bheinsius@gmail.com> <mailto:bheinsius@gmail.com> &nbs= p;wrote:



Hi,

I read some time ago that Xen does not have assembly-language mutex support= .
Is this still the case in Xen 3.2?

best regards,
Bart.

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/x= en-devel




____________________= ___________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/x= en-devel

--B_3290234657_22397944-- --===============1866299738== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel --===============1866299738==--