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RE: [Xen-ia64-devel] unaligned access handler deadlock when a userapplication runs in big endian mode ( psr.be is set )


  • To: "Gareth Knight" <gareth@xxxxxxxxxxxxxx>, <xen-ia64-devel@xxxxxxxxxxxxxxxxxxx>
  • From: "Xu, Anthony" <anthony.xu@xxxxxxxxx>
  • Date: Fri, 25 Aug 2006 09:32:44 +0800
  • Delivery-date: Thu, 24 Aug 2006 18:33:14 -0700
  • List-id: Discussion of the ia64 port of Xen <xen-ia64-devel.lists.xensource.com>
  • Thread-index: AcbH2UwMkVluA0uXTcibjc4RCf9mvgADATwg
  • Thread-topic: [Xen-ia64-devel] unaligned access handler deadlock when a userapplication runs in big endian mode ( psr.be is set )

Hi Gareth

Handling big endian mode is an interesting topic.
Frankly, In VTI side, we didn't handle big endian mode, and we knew this is 
an issue.
I would like to look at this issue.

Did you run this application on domU or VTI-domain?


Thanks
Anthony

>-----Original Message-----
>From: xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx
>[mailto:xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Gareth
>Knight
>Sent: 2006?8?25? 7:58
>To: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
>Subject: [Xen-ia64-devel] unaligned access handler deadlock when a
>userapplication runs in big endian mode ( psr.be is set )
>
>All,
>
>Repost sans confidentiality notice !
>
>I've got top of tree xen-ia64-unstable.hg running on my Tiger
>system.  I'm working on getting our (Transitive's) QuickTransit
>dynamic binary translator working in a guest machine.  QuickTransit
>Sparc Solaris -> ia64 linux makes use of the big endian mode to speed
>up its translation of Sparc applications.
>
>I've tried adding a "rum psr.be" in all the interrupt vectors near
>the top and that certainly improves matters, but it also causes the
>unaligned access handler to believe the user app is running in little
>endian mode, which is not true.  I've put together an example to
>demonstrate the issue.  The source is attached below.  Basically the
>example tries to do an unaligned access whilst in big endian mode,
>which when running correctly currently produces a SIGBUS ( since the
>Linux kernel currently has no big endian unaligned access
>handling ).  On the Xen kernel it currently deadlocks.
>
>Comments welcome,
>
>Gareth.

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