Hello, I'm having a problem, I've seen other people with the same problem, but with USB. Some people solved this with the pciback.permissive option, but in my case it's ignored. I'm using CentOS 5.2 - 2.6.18-92.1.10.el5.centos.plusxen The error return from the console starting the domU is below. I've tried swiotlb=force, pciback.permissive like I said. My configs are: /etc/modprobe.conf ... options pciback hide=(03:01.0) # cat /etc/xen//firewall name = "firewall" uuid = "cd5f6ad8-0682-73fd-3268-fb4a7b85c0ec" maxmem = 256 memory = 256 vcpus = 1 bootloader = "/usr/bin/pygrub" boot = "swiotlb=force" on_poweroff = "destroy" on_reboot = "restart" on_crash = "restart" vfb = [ "type=vnc,vncunused=1" ] disk = [ "phy:/dev/VolGroup00/firewall.disk,xvda,w" ] vif = [ "mac=00:16:3e:0e:53:5a,bridge=virbr0" ] pci = [ '0000:03:01.0' ] # rpm -qa | grep xen xen-libs-3.0.3-64.el5_2.1 xen-3.0.3-64.el5_2.1 kernel-xen-2.6.18-92.el5 kernel-xen-2.6.18-92.1.10.el5.centos.plus --- Iniciando interface eth0: [ OK ] Iniciando interface eth1: Determinando informa??o IP para o eth1...Fatal DMA error! Please use 'swiotlb=force' ------------[ cut here ]------------ kernel BUG at arch/i386/kernel/pci-dma-xen.c:401! invalid opcode: 0000 [#1] SMP last sysfs file: /class/net/eth1/address Modules linked in: xennet ip_conntrack_netbios_ns ipt_REJECT xt_state ip_conntrack nfnetlink iptable_filter ip_tables ip6t_REJECT xt_tcpudp ip6table_filter ip6_tables x_tables ipv6 xfrm_nalgo crypto_api dm_mirror dm_multipath dm_mod parport_pc lp parport 3c59x pcspkr mii xenblk ext3 jbd uhci_hcd ohci_hcd ehci_hcd CPU: 0 EIP: 0061:[<c040a39c>] Not tainted VLI EFLAGS: 00010292 (2.6.18-92.el5xen #1) EIP is at dma_map_single+0x12d/0x147 eax: 0000002f ebx: 00000000 ecx: 00000001 edx: f5416000 esi: 38f59e02 edi: 00000001 ebp: 0000004e esp: c071bdbc ds: 007b es: 007b ss: 0069 Process swapper (pid: 0, ti=c071b000 task=c066e2c0 task.ti=c06e6000) Stack: c0621abd c07fc448 008a8e02 00000000 cf914400 cf5db200 c07fc448 00000140 d1232e6e 00000001 c08a8e02 cf914000 cf88c200 00000002 cf5db200 0000004e d126c000 cf914000 0000004e c08a8e02 cf88c140 cf88c140 cf88c200 c07c4c88 Call Trace: [<d1232e6e>] boomerang_start_xmit+0x141/0x352 [3c59x] [<c05aec59>] dev_hard_start_xmit+0x198/0x1ee [<c05bcaf6>] __qdisc_run+0xe4/0x19a [<c05b0544>] dev_queue_xmit+0x1e0/0x2e8 [<c05b4b24>] neigh_resolve_output+0x1b2/0x1dc [<d136eb2e>] ip6_output2+0x256/0x2a7 [ipv6] [<d136f656>] ip6_output+0x9c7/0x9f3 [ipv6] [<d137c8c0>] dst_output+0x0/0x7 [ipv6] [<c05c3d12>] nf_hook_slow+0x3a/0x90 [<d137c8c0>] dst_output+0x0/0x7 [ipv6] [<d137e4d6>] ndisc_send_ns+0x3a8/0x47a [ipv6] [<c06090d8>] _spin_lock_irqsave+0x8/0x28 [<c042914a>] lock_timer_base+0x15/0x2f [<d1375ddb>] addrconf_dad_timer+0xc3/0xdf [ipv6] [<c0434244>] hrtimer_run_queues+0x14b/0x163 [<d1375d18>] addrconf_dad_timer+0x0/0xdf [ipv6] [<c0429600>] run_timer_softirq+0x101/0x15c [<c042613e>] __do_softirq+0x5e/0xc3 [<c0406edf>] do_softirq+0x56/0xaf [<c0406e80>] do_IRQ+0xa5/0xae [<c0549913>] evtchn_do_upcall+0x64/0x9b [<c04055d9>] hypervisor_callback+0x3d/0x48 [<c0408632>] raw_safe_halt+0x8c/0xaf [<c040321a>] xen_idle+0x22/0x2e [<c0403339>] cpu_idle+0x91/0xab [<c06eb9f5>] start_kernel+0x37a/0x381 ======================Code: c0 74 07 8b 08 8b 58 04 eb 05 83 c9 ff 31 db 89 da 89 c8 f7 d2 f7 d0 21 fa 21 f0 89 d1 09 c1 74 13 68 bd 1a 62 c0 e8 de 7b 01 00 <0f> 0b 91 01 9e 1a 62 c0 5d f0 83 04 24 00 83 c4 0c 89 f0 89 fa EIP: [<c040a39c>] dma_map_single+0x12d/0x147 SS:ESP 0069:c071bdbc <0>Kernel panic - not syncing: Fatal exception in interrupt --- If you need more information, just tell -- Enderson Maia