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...