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[Xen-users] DMA and Configuration read issues

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Subject: [Xen-users] DMA and Configuration read issues
From: "Byrne, Nicholas" <Nicholas.Byrne@xxxxxxxxxxxx>
Date: Wed, 6 Sep 2006 14:59:47 +0100
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Thread-topic: DMA and Configuration read issues
We've deployed Xen 3.0.2-2 successfully on a CentOS 4.3 installation running on 
a Dell PE 2950 servers. On a HVM/VMX guest also running CentOS 4.3 with the 
configuration below, we see occasional DMA messages in the guests dmesg output, 
they don't occur often and for no obvious reason - it seems they normally occur 
when the load on the host system is low.
hda: dma_timer_expiry: dma status == 0x24 
hda: DMA interrupt recovery 
hda: lost interrupt 
Windows 2003 server guests on the same host system don't appear to have any 
problems (at least none are logged), but two Linux guests do, the above one 
CentOS and a Fedora core 3 system. Does anyone have any idea how to solve this? 
<Start Config>
import os, re
arch = os.uname()[4]
if re.search('64', arch):
    arch_libdir = 'lib64'
    arch_libdir = 'lib'
kernel = "/usr/lib/xen/boot/hvmloader"
memory = 256
name = "CentOS4.3_01"
vif = [ 'type=ioemu, bridge=xenbr0' ]
disk = [ 'phy:/dev/XEN/CentOS4.3_01,ioemu:hda,w' ]
device_model = '/usr/' + arch_libdir + '/xen/bin/qemu-dm'
#cdrom = '/dev/hda'
<End Config>
The second problem we've encountered, which appears not to be listed in the bug 
tracker. When any one of these guests is rebooted from inside the guest, some 
of the xen guest configuration appears not to be re-read/re-used. For example, 
we have noticed this when we have statically allocated the host cpu's each 
guest should run on; after a reboot (viewing "xm vcpu-list") the CPU Affinity 
changes from the defined one to "any cpu".

Any help appreciated


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