Hi,
Well, just tried what you suggested, and here 
        are the results:
* If i comment the 'clear_fault_bits()' call - then 
        Xen boots ok, with iommu=1
The strange thing, is that after it booted 
        one time ok (with the second patch), then it continued to boot ok, even 
        if i reverted the second patch.
The relevant lines in the log 
        are:
(XEN) clear_fault_bits: CAP_REG=0xc0000020630270
(XEN) 
        clear_fault_bits: CAP_REG=0xc0000020630260
(XEN) clear_fault_bits: 
        CAP_REG=0xc9008020e30260
(XEN) clear_fault_bits: 
        CAP_REG=0xc9008020630260
Anyway, here is the full Xen log, with 
        the first patch (print cap's) applied:
__  
        __            
        _____ _  _    ___  
 \ \/ /___ _ 
        __   |___ /| || |  / _ \ 
  \  // _ \ '_ 
        \    |_ \| || |_| | | |
  /  \  __/ | | 
        |  ___) |__   _| |_| |
 /_/\_\___|_| |_| |____(_) 
        |_|(_)___/ 
                                              
        
(XEN) Xen version 3.4.0 (root@[unknown]) (gcc version 4.3.2 (Debian 
        4.3.2-1.1) ) Mon Jun 29 07:53:38 EDT 2009
(XEN) Latest ChangeSet: Wed 
        Jun 24 11:15:04 2009 +0300 19629:b2128a88e3dd
(XEN) Command line: 
        console=com1 com1=115200,8n1 iommu=1 iommu_inclusive_mapping loglvl=all 
        guest_loglvl=all
(XEN) Video information:
(XEN)  VGA is text 
        mode 80x25, font 8x16
(XEN)  VBE/DDC methods: V2; EDID transfer 
        time: 1 seconds
(XEN) Disc information:
(XEN)  Found 1 MBR 
        signatures
(XEN)  Found 1 EDD information structures
(XEN) 
        Xen-e820 RAM map:
(XEN)  0000000000000000 - 000000000009f000 
        (usable)
(XEN)  000000000009f000 - 00000000000a0000 
        (reserved)
(XEN)  0000000000100000 - 000000007c04d400 
        (usable)
(XEN)  000000007c04d400 - 000000007c04f400 (ACPI 
        NVS)
(XEN)  000000007c04f400 - 000000007f000000 
        (reserved)
(XEN)  00000000f8000000 - 00000000fc000000 
        (reserved)
(XEN)  00000000fec00000 - 00000000fec10000 
        (reserved)
(XEN)  00000000fed18000 - 00000000fed1c000 
        (reserved)
(XEN)  00000000fed20000 - 00000000fed90000 
        (reserved)
(XEN)  00000000feda0000 - 00000000feda6000 
        (reserved)
(XEN)  00000000fee00000 - 00000000fee10000 
        (reserved)
(XEN)  00000000ffe60000 - 0000000100000000 
        (reserved)
(XEN) System RAM: 1983MB (2031536kB)
(XEN) ACPI: RSDP 
        000FB9C0, 0024 (r2 DELL  )
(XEN) ACPI: XSDT 7C051E00, 006C (r1 
        DELL    M09     27D9020D 
        ASL        61)
(XEN) ACPI: FACP 
        7C051C9C, 00F4 (r4 DELL    M09     
        27D9020D ASL        61)
(XEN) 
        ACPI: DSDT 7C052400, 6A2B (r2 INT430 SYSFexxx     
        1001 INTL 20050624)
(XEN) ACPI: FACS 7C060C00, 0040
(XEN) ACPI: 
        HPET 7C051F00, 0038 (r1 DELL    
        M09            1 
        ASL        61)
(XEN) ACPI: DMAR 
        7C060400, 0120 (r1 DELL    M09     
        27D9020D ASL        61)
(XEN) 
        ACPI: APIC 7C052000, 0068 (r1 DELL    
        M09     27D9020D 
        ASL        47)
(XEN) ACPI: ASF! 
        7C051C00, 006A (r32 DELL    M09     
        27D9020D ASL        61)
(XEN) 
        ACPI: MCFG 7C051FC0, 003E (r16 DELL    
        M09     27D9020D 
        ASL        61)
(XEN) ACPI: TCPA 
        7C052300, 0032 
        (r1                        
        0 ASL         0)
(XEN) ACPI: 
        SLIC 7C05209C, 0176 (r1 DELL    
        M09     27D9020D 
        ASL        61)
(XEN) ACPI: SSDT 
        7C05032D, 066C (r1  PmRef    
        CpuPm     3000 INTL 20050624)
(XEN) NUMA turned 
        off
(XEN) Faking a node at 0000000000000000-000000007c04d000
(XEN) 
        Domain heap initialised
(XEN) DMI 2.4 present.
(XEN) Using APIC 
        driver default
(XEN) ACPI: PM-Timer IO Port: 0x1008
(XEN) ACPI: 
        ACPI SLEEP INFO: pm1x_cnt[1004,0], pm1x_evt[1000,0]
(XEN) 
        ACPI:                  
        wakeup_vec[7c060c0c], vec_size[20]
(XEN) ACPI: Local APIC address 
        0xfee00000
(XEN) ACPI: LAPIC (acpi_id[0x00] lapic_id[0x00] 
        enabled)
(XEN) Processor #0 7:7 APIC version 20
(XEN) ACPI: LAPIC 
        (acpi_id[0x01] lapic_id[0x01] enabled)
(XEN) Processor #1 7:7 APIC 
        version 20
(XEN) ACPI: LAPIC_NMI (acpi_id[0x00] high edge 
        lint[0x1])
(XEN) ACPI: LAPIC_NMI (acpi_id[0x01] high edge 
        lint[0x1])
(XEN) ACPI: IOAPIC (id[0x02] address[0xfec00000] 
        gsi_base[0])
(XEN) IOAPIC[0]: apic_id 2, version 32, address 
        0xfec00000, GSI 0-23
(XEN) ACPI: INT_SRC_OVR (bus 0 bus_irq 0 
        global_irq 2 dfl dfl)
(XEN) ACPI: INT_SRC_OVR (bus 0 bus_irq 9 
        global_irq 9 high level)
(XEN) ACPI: IRQ0 used by override.
(XEN) 
        ACPI: IRQ2 used by override.
(XEN) ACPI: IRQ9 used by 
        override.
(XEN) Enabling APIC mode:  Flat.  Using 1 I/O 
        APICs
(XEN) ACPI: HPET id: 0x8086a201 base: 0xfed00000
(XEN) 
        [VT-D]dmar.c:485: Host address width 36
(XEN) [VT-D]dmar.c:494: found 
        ACPI_DMAR_DRHD
(XEN) [VT-D]dmar.c:349: dmaru->address = 
        fed10000
(XEN) [VT-D]dmar.c:300: found endpoint: bdf = 
        0:1b.0
(XEN) [VT-D]dmar.c:494: found ACPI_DMAR_DRHD
(XEN) 
        [VT-D]dmar.c:349: dmaru->address = fed11000
(XEN) 
        [VT-D]dmar.c:300: found endpoint: bdf = 0:2.0
(XEN) [VT-D]dmar.c:300: 
        found endpoint: bdf = 0:2.1
(XEN) [VT-D]dmar.c:494: found 
        ACPI_DMAR_DRHD
(XEN) [VT-D]dmar.c:349: dmaru->address = 
        fed12000
(XEN) [VT-D]dmar.c:300: found endpoint: bdf = 0:3.0
(XEN) 
        [VT-D]dmar.c:300: found endpoint: bdf = 0:3.2
(XEN) [VT-D]dmar.c:300: 
        found endpoint: bdf = 0:3.3
(XEN) [VT-D]dmar.c:494: found 
        ACPI_DMAR_DRHD
(XEN) [VT-D]dmar.c:349: dmaru->address = 
        fed13000
(XEN) [VT-D]dmar.c:358: found INCLUDE_ALL
(XEN) 
        [VT-D]dmar.c:498: found ACPI_DMAR_RMRR
(XEN) [VT-D]dmar.c:300: found 
        endpoint: bdf = 0:1d.0
(XEN) [VT-D]dmar.c:300: found endpoint: bdf = 
        0:1d.1
(XEN) [VT-D]dmar.c:300: found endpoint: bdf = 0:1d.2
(XEN) 
        [VT-D]dmar.c:300: found endpoint: bdf = 0:1d.7
(XEN) 
        [VT-D]dmar.c:300: found endpoint: bdf = 0:1a.0
(XEN) 
        [VT-D]dmar.c:300: found endpoint: bdf = 0:1a.1
(XEN) 
        [VT-D]dmar.c:300: found endpoint: bdf = 0:1a.2
(XEN) 
        [VT-D]dmar.c:300: found endpoint: bdf = 0:1a.7
(XEN) 
        [VT-D]dmar.c:498: found ACPI_DMAR_RMRR
(XEN) [VT-D]dmar.c:300: found 
        endpoint: bdf = 0:2.0
(XEN) [VT-D]dmar.c:300: found endpoint: bdf = 
        0:2.1
(XEN) Intel VT-d DMAR tables have been parsed.
(XEN) Using 
        ACPI (MADT) for SMP configuration information
(XEN) Using scheduler: 
        SMP Credit Scheduler (credit)
(XEN) Initializing CPU#0
(XEN) 
        Detected 2527.068 MHz processor.
(XEN) CPU: L1 I cache: 32K, L1 D 
        cache: 32K
(XEN) CPU: L2 cache: 6144K
(XEN) CPU: Physical 
        Processor ID: 0
(XEN) CPU: Processor Core ID: 0
(XEN) VMX: 
        Supported advanced features:
(XEN)  - APIC MMIO access 
        virtualisation
(XEN)  - APIC TPR shadow
(XEN)  - Virtual 
        NMI
(XEN)  - MSR direct-access bitmap
(XEN) HVM: VMX 
        enabled
(XEN) Intel machine check reporting enabled on 
        CPU#0.
(XEN) mce_init: init bank1
(XEN) mce_init: init 
        bank2
(XEN) mce_init: init bank3
(XEN) mce_init: init 
        bank4
(XEN) mce_init: init bank5
(XEN) CPU0: Thermal monitoring 
        enabled (TM2)
(XEN) CMCI: CPU0 has no CMCI support
(XEN) CPU0: 
        Intel(R) Core(TM)2 Duo CPU     T9400  @ 2.53GHz 
        stepping 06
(XEN) Booting processor 1/1 eip 8c000
(XEN) 
        Initializing CPU#1
(XEN) CPU: L1 I cache: 32K, L1 D cache: 
        32K
(XEN) CPU: L2 cache: 6144K
(XEN) CPU: Physical Processor ID: 
        0
(XEN) CPU: Processor Core ID: 1
(XEN) Intel machine check 
        reporting enabled on CPU#1.
(XEN) mce_init: init bank1
(XEN) 
        mce_init: init bank2
(XEN) mce_init: init bank4
(XEN) mce_init: 
        init bank5
(XEN) CPU1: Thermal monitoring enabled (TM2)
(XEN) 
        CMCI: CPU1 has no CMCI support
(XEN) CPU1: Intel(R) Core(TM)2 Duo 
        CPU     T9400  @ 2.53GHz stepping 06
(XEN) 
        Total of 2 processors activated.
(XEN) ENABLING IO-APIC 
        IRQs
(XEN)  -> Using new ACK method
(XEN) ..TIMER: 
        vector=0xF0 apic1=0 pin1=2 apic2=-1 pin2=-1
(XEN) checking TSC 
        synchronization across 2 CPUs: passed.
(XEN) Platform timer is 
        14.318MHz HPET
(XEN) Brought up 2 CPUs
(XEN) microcode.c:73:d32767 
        microcode: CPU1 resumed
(XEN) [VT-D]iommu.c:1763: DMAR: Forcing 
        write-buffer flush
(XEN) Intel VT-d Snoop Control not 
        supported.
(XEN) Intel VT-d DMA Passthrough not supported.
(XEN) 
        Intel VT-d Queued Invalidation not supported.
(XEN) Intel VT-d 
        Interrupt Remapping not supported.
(XEN) clear_fault_bits: 
        CAP_REG=0xc0000020630270
(XEN) clear_fault_bits: 
        CAP_REG=0xc0000020630260
(XEN) clear_fault_bits: 
        CAP_REG=0xc9008020e30260
(XEN) clear_fault_bits: 
        CAP_REG=0xc9008020630260
(XEN) I/O virtualisation enabled
(XEN) 
        I/O virtualisation for PV guests disabled
(XEN) HPET: 4 timers in 
        total, 0 timers will be used for broadcast
(XEN) ACPI sleep modes: 
        S3
(XEN) mcheck_poll: Machine check polling timer started.
(XEN) 
        [VT-D]iommu.c:1252:d32767 domain_context_mapping:PCI: bdf = 
        0:0.0
(XEN) [VT-D]iommu.c:1252:d32767 domain_context_mapping:PCI: bdf 
        = 0:2.0
(XEN) [VT-D]iommu.c:1252:d32767 domain_context_mapping:PCI: 
        bdf = 0:2.1
(XEN) [VT-D]iommu.c:1252:d32767 
        domain_context_mapping:PCI: bdf = 0:3.0
(XEN) 
        [VT-D]iommu.c:1252:d32767 domain_context_mapping:PCI: bdf = 
        0:3.2
(XEN) [VT-D]iommu.c:1252:d32767 domain_context_mapping:PCI: bdf 
        = 0:3.3
(XEN) [VT-D]iommu.c:1252:d32767 domain_context_mapping:PCI: 
        bdf = 0:19.0
(XEN) [VT-D]iommu.c:1252:d32767 
        domain_context_mapping:PCI: bdf = 0:1a.0
(XEN) 
        [VT-D]iommu.c:1252:d32767 domain_context_mapping:PCI: bdf = 
        0:1a.1
(XEN) [VT-D]iommu.c:1252:d32767 domain_context_mapping:PCI: 
        bdf = 0:1a.2
(XEN) [VT-D]iommu.c:1252:d32767 
        domain_context_mapping:PCI: bdf = 0:1a.7
(XEN) 
        [VT-D]iommu.c:1245:d32767 domain_context_mapping:PCIe: bdf = 
        0:1b.0
(XEN) [VT-D]iommu.c:1252:d32767 domain_context_mapping:PCI: 
        bdf = 0:1d.0
(XEN) [VT-D]iommu.c:1252:d32767 
        domain_context_mapping:PCI: bdf = 0:1d.1
(XEN) 
        [VT-D]iommu.c:1252:d32767 domain_context_mapping:PCI: bdf = 
        0:1d.2
(XEN) [VT-D]iommu.c:1252:d32767 domain_context_mapping:PCI: 
        bdf = 0:1d.7
(XEN) [VT-D]iommu.c:1252:d32767 
        domain_context_mapping:PCI: bdf = 0:1f.0
(XEN) 
        [VT-D]iommu.c:1252:d32767 domain_context_mapping:PCI: bdf = 
        0:1f.2
(XEN) [VT-D]iommu.c:1252:d32767 domain_context_mapping:PCI: 
        bdf = 0:1f.3
(XEN) [VT-D]iommu.c:1245:d32767 
        domain_context_mapping:PCIe: bdf = c:0.0
(XEN) 
        [VT-D]iommu.c:1252:d32767 domain_context_mapping:PCI: bdf = 
        0:2.0
(XEN) [VT-D]iommu.c:1252:d32767 domain_context_mapping:PCI: bdf 
        = 0:2.1
(XEN) [VT-D]iommu.c:1252:d32767 domain_context_mapping:PCI: 
        bdf = 0:1d.0
(XEN) [VT-D]iommu.c:1252:d32767 
        domain_context_mapping:PCI: bdf = 0:1d.1
(XEN) 
        [VT-D]iommu.c:1252:d32767 domain_context_mapping:PCI: bdf = 
        0:1d.2
(XEN) [VT-D]iommu.c:1252:d32767 domain_context_mapping:PCI: 
        bdf = 0:1d.7
(XEN) [VT-D]iommu.c:1252:d32767 
        domain_context_mapping:PCI: bdf = 0:1a.0
(XEN) 
        [VT-D]iommu.c:1252:d32767 domain_context_mapping:PCI: bdf = 
        0:1a.1
(XEN) [VT-D]iommu.c:1252:d32767 domain_context_mapping:PCI: 
        bdf = 0:1a.2
(XEN) [VT-D]iommu.c:1252:d32767 
        domain_context_mapping:PCI: bdf = 0:1a.7
(XEN) [VT-D]iommu.c:620: 
        iommu_enable_translation: iommu->reg = ffff828bfff57000
(XEN) 
        [VT-D]iommu.c:620: iommu_enable_translation: iommu->reg = 
        ffff828bfff56000
(XEN) [VT-D]iommu.c:620: iommu_enable_translation: 
        iommu->reg = ffff828bfff55000
(XEN) [VT-D]iommu.c:620: 
        iommu_enable_translation: iommu->reg = ffff828bfff54000
(XEN) *** 
        LOADING DOMAIN 0 ***
(XEN)  Xen  kernel: 64-bit, lsb, 
        compat32
(XEN)  Dom0 kernel: 64-bit, lsb, paddr 
        0xffffffff80200000 -> 0xffffffff8070ab48
(XEN) PHYSICAL MEMORY 
        ARRANGEMENT:
(XEN)  Dom0 alloc.:   
        0000000076000000->0000000078000000 (460259 pages to be 
        allocated)
(XEN) VIRTUAL MEMORY ARRANGEMENT:
(XEN)  Loaded 
        kernel: ffffffff80200000->ffffffff8070ab48
(XEN)  Init. 
        ramdisk: ffffffff8070b000->ffffffff81b94400
(XEN)  Phys-Mach 
        map: ffffffff81b95000->ffffffff81f27f18
(XEN)  Start 
        info:    
        ffffffff81f28000->ffffffff81f284b4
(XEN)  Page 
        tables:   ffffffff81f29000->ffffffff81f3c000
(XEN)  
        Boot stack:    
        ffffffff81f3c000->ffffffff81f3d000
(XEN)  
        TOTAL:         
        ffffffff80000000->ffffffff82000000
(XEN)  ENTRY ADDRESS: 
        ffffffff80200000
(XEN) Dom0 has maximum 2 VCPUs
(XEN) Scrubbing 
        Free RAM: .done.
(XEN) Xen trace buffers: disabled
(XEN) Std. 
        Loglevel: All
(XEN) Guest Loglevel: All
(XEN) *** Serial input 
        -> DOM0 (type 'CTRL-a' three times to switch input to Xen)
(XEN) 
        Freed 132kB init memory.
Tom
        
2009/6/29 Cui, Dexuan 
<dexuan.cui@xxxxxxxxx>
        
          diff -r 90391e2247fc xen/drivers/passthrough/vtd/iommu.c
--- 
          a/xen/drivers/passthrough/vtd/iommu.c   Tue Jun 23 11:40:27 2009 
          +0100
+++ b/xen/drivers/passthrough/vtd/iommu.c   Mon 
          Jun 29 10:24:31 2009 +0800
@@ -1693,7 +1693,7 @@ static int 
          init_vtd_hw(void)
        }
    
              dma_msi_data_init(iommu, iommu->vector);
  
                dma_msi_addr_init(iommu, 
          cpu_physical_id(first_cpu(cpu_online_map)));
-       
           clear_fault_bits(iommu);
+       
           //clear_fault_bits(iommu);
        
          dmar_writel(iommu->reg, DMAR_FECTL_REG, 0);
    
              /* initialize flush functions */
And, can you 
          comment the invocation of clear_fault_bits() in init_vtd_hw() like 
          above and see if the host can boot fine?
Thanks,
-- Dexuan
          -----Original Message-----
From: Cui, 
          Dexuan
Sent: 2009?6?29? 14:30
To: 'Tom Rotenberg'; 
xen-devel@xxxxxxxxxxxxxxxxxxxSubject: RE: 
          [Xen-devel] Problem: Xen 3.4 fails to boot on Dell e6400, with 
          iommu=1
diff -r 90391e2247fc 
          xen/drivers/passthrough/vtd/iommu.c
--- 
          a/xen/drivers/passthrough/vtd/iommu.c   Tue Jun 23 11:40:27 2009 
          +0100
+++ b/xen/drivers/passthrough/vtd/iommu.c   Mon Jun 29 
          10:18:23 2009 +0800
@@ -1653,6 +1653,8 @@ void 
          clear_fault_bits(struct iommu *iomm
 {
    u64 
          val;
+    printk("clear_fault_bits: 
          CAP_REG=0x%llx\n",
+        (unsigned long 
          long)dmar_readq(iommu->reg,DMAR_CAP_REG));
    val = 
          dmar_readq(
        iommu->reg,
  
                
          cap_fault_reg_offset(dmar_readq(iommu->reg,DMAR_CAP_REG))+0x8);
Hi 
          Tom,
Can you please apply the above patch and send us the entire 
          log?
(I don't have the same host, so I can't try it 
          myself.)
Thanks,
-- 
          Dexuan
________________________________
From: 
xen-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:
xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of 
          Tom Rotenberg
Sent: 2009?6?28? 22:56
To: 
xen-devel@xxxxxxxxxxxxxxxxxxxSubject: 
          [Xen-devel] Problem: Xen 3.4 fails to boot on Dell e6400, with 
          iommu=1
 
          
          
          Hi,
I am trying to use xen 3.4 on a Dell E6400 machine. 
          But, when i try to boot xen with a 'iommu=1' parameter in the boot 
          line, Xen fails to boot. I have also tried to boot with and without 
          the 'iommu_inclusive_mapping' boot option, but it didn't seem to help 
          at all.
Does anyone knows how to solve this issue?
These 
          are the last messages in the UART:
(XEN) Brought up 2 
          CPUs
(XEN) microcode.c:73:d32767 microcode: CPU1 resumed
(XEN) 
          [VT-D]iommu.c:1761: DMAR: Forcing write-buffer flush
(XEN) Intel 
          VT-d Snoop Control supported.
(XEN) Intel VT-d DMA Passthrough not 
          supported.
(XEN) Intel VT-d Queued Invalidation supported.
(XEN) 
          Intel VT-d Interrupt Remapping supported.
(XEN) ----[ Xen-3.4.0 
           x86_64  debug=n  Not tainted ]----
(XEN) CPU: 
             0
(XEN) RIP:   
           e008:[<ffff828c8012c951>] 
          clear_fault_bits+0x21/0xa0
(XEN) RFLAGS: 0000000000010202   
          CONTEXT: hypervisor
(XEN) rax: ffff828bfff5aff8   rbx: 
          ffff830078f82f90   rcx: 0000000000000020
(XEN) rdx: 
          00000000ffffffff   rsi: ffff828bfff57000   rdi: 
          ffff830078f82f90
(XEN) rbp: 0000000000000090   rsp: 
          ffff828c8026fda0   r8:  ffff83007be2c110
(XEN) r9: 
           000000000000001a   r10: 0000000000000005   r11: 
          0000000000000005
(XEN) r12: 0000000000000090   r13: 
          0000000000000090   r14: ffff830078f82fcc
(XEN) r15: 
          0000000000004800   cr0: 000000008005003b   cr4: 
          00000000000026f0
(XEN) cr3: 000000007be74000   cr2: 
          ffff828bfff5aff8
(XEN) ds: 0000   es: 0000   fs: 0000 
            gs: 0000   ss: 0000   cs: e008
(XEN) Xen stack 
          trace from rsp=ffff828c8026fda0:
(XEN)   
           ffff828c8012d32d ffff830078f824b0 ffff828c801e422f 
          ffff828c80204490
(XEN)    ffff828c801e422f 
          ffff828c802044c0 ffff828c8026fdf8 0000000000000000
(XEN)   
           ffff828c8012de7e ffff830078f82d40 ffff828c80228100 
          000000000000001f
(XEN)    00000000ffffffed 
          ffff828c80227a78 0000000000000001 ffff828c80205f60
(XEN)   
           ffff828c801f3400 ffff83000008bf40 ffff828c8012a9d4 
          ffff828c80227978
(XEN)    ffff828c8021a589 
          0000000000000000 0000000000000000 0000000000000000
(XEN)   
           0000000000000000 0000000000000000 0000000000000000 
          0000000000000000
(XEN)    00000000002b23c0 
          ffffff8c80274000 0008bf4000000000 000000000008bf40
(XEN)   
           0000000000000000 ffff83000008bfc0 0000000001ce08a0 
          0000000000000000
(XEN)    ffffffff00000000 
          0000000800000000 000000010000006e 0000000000000003
(XEN)   
           00000000000002f8 0000000000000000 0000000000000000 
          0000000000067e2c
(XEN)    0000000000000000 
          0000000000000000 0000000000000000 0000000000000000
(XEN)   
           ffff828c801000b5 0000000000000000 0000000000000000 
          0000000000000000
(XEN)    0000000000000000 
          0000000000000000 0000000000000000 0000000000000000
(XEN)   
           0000000000000000 0000000000000000 0000000000000000 
          0000000000000000
(XEN)    0000000000000000 
          0000000000000000 0000000000000000 0000000000000000
(XEN)   
           0000000000000000 0000000000000000 0000000000000000 
          0000000000000000
(XEN)    0000000000000000 
          0000000000000000 0000000000000000 0000000000000000
(XEN)   
           0000000000000000 0000000000000000 0000000000000000 
          ffff830079f18000
(XEN) Xen call trace:
(XEN)   
           [<ffff828c8012c951>] clear_fault_bits+0x21/0xa0
(XEN) 
             [<ffff828c8012d32d>] 
          init_vtd_hw+0x15d/0x3e0
(XEN)   
           [<ffff828c8012de7e>] intel_vtd_setup+0x5ae/0x610
(XEN) 
             [<ffff828c8012a9d4>] 
          iommu_setup+0x24/0x110
(XEN)   
           [<ffff828c8021a589>] __start_xen+0x1859/0x27c0
(XEN) 
             [<ffff828c801000b5>] 
          __high_start+0xa1/0xa3
(XEN)
(XEN) Pagetable walk from 
          ffff828bfff5aff8:
(XEN)  L4[0x105] = 000000007be7a027 
          5555555555555555
(XEN)  L3[0x02f] = 000000007c04b063 
          5555555555555555
(XEN)  L2[0x1ff] = 000000007c04a063 
          5555555555555555
(XEN)  L1[0x15a] = 0000000000000000 
          ffffffffffffffff
(XEN)
(XEN) 
          ****************************************
(XEN) Panic on CPU 
          0:
(XEN) FATAL PAGE FAULT
(XEN) [error_code=0000]
(XEN) 
          Faulting linear address: ffff828bfff5aff8
(XEN) 
          ****************************************
(XEN)
(XEN) Reboot in 
          five 
        seconds...