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    Subject[PATCH] Blacklist DMAR on Intel G31/G33 chipsets
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    Date
    Some BIOSes (the Intel DG33BU, for example) wrongly claim to have DMAR
    when they don't. Avoid the resulting crashes when it doesn't work as
    expected.

    Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
    ---

    This time, I build-tested it with CONFIG_DMAR actually enabled. Sorry.
    I'd still be grateful if someone could test it on a DG33BU with the old
    BIOS though, since I've killed mine. I tested the DMI version, but not
    this one.

    arch/x86/kernel/early-quirks.c | 18 ++++++++++++++++++
    drivers/pci/intel-iommu.c | 2 +-
    include/asm-x86/iommu.h | 1 +
    3 files changed, 20 insertions(+), 1 deletions(-)

    diff --git a/arch/x86/kernel/early-quirks.c b/arch/x86/kernel/early-quirks.c
    index 4353cf5..24bb5fa 100644
    --- a/arch/x86/kernel/early-quirks.c
    +++ b/arch/x86/kernel/early-quirks.c
    @@ -95,6 +95,20 @@ static void __init nvidia_bugs(int num, int slot, int func)

    }

    +#ifdef CONFIG_DMAR
    +static void __init intel_g33_dmar(int num, int slot, int func)
    +{
    + struct acpi_table_header *dmar_tbl;
    + acpi_status status;
    +
    + status = acpi_get_table(ACPI_SIG_DMAR, 0, &dmar_tbl);
    + if (ACPI_SUCCESS(status)) {
    + printk(KERN_INFO "BIOS BUG: DMAR advertised on Intel G31/G33 chipset -- ignoring\n");
    + dmar_disabled = 1;
    + }
    +}
    +#endif
    +
    #define QFLAG_APPLY_ONCE 0x1
    #define QFLAG_APPLIED 0x2
    #define QFLAG_DONE (QFLAG_APPLY_ONCE|QFLAG_APPLIED)
    @@ -114,6 +128,10 @@ static struct chipset early_qrk[] __initdata = {
    PCI_CLASS_BRIDGE_PCI, PCI_ANY_ID, QFLAG_APPLY_ONCE, via_bugs },
    { PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_K8_NB,
    PCI_CLASS_BRIDGE_HOST, PCI_ANY_ID, 0, fix_hypertransport_config },
    +#ifdef CONFIG_DMAR
    + { PCI_VENDOR_ID_INTEL, 0x29c0,
    + PCI_CLASS_BRIDGE_HOST, PCI_ANY_ID, 0, intel_g33_dmar },
    +#endif
    {}
    };

    diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
    index 8d0e60a..eaba6ec 100644
    --- a/drivers/pci/intel-iommu.c
    +++ b/drivers/pci/intel-iommu.c
    @@ -80,7 +80,7 @@ static long list_size;

    static void domain_remove_dev_info(struct dmar_domain *domain);

    -static int dmar_disabled;
    +int dmar_disabled;
    static int __initdata dmar_map_gfx = 1;
    static int dmar_forcedac;
    static int intel_iommu_strict;
    diff --git a/include/asm-x86/iommu.h b/include/asm-x86/iommu.h
    index 5f888cc..621a1af 100644
    --- a/include/asm-x86/iommu.h
    +++ b/include/asm-x86/iommu.h
    @@ -6,6 +6,7 @@ extern void no_iommu_init(void);
    extern struct dma_mapping_ops nommu_dma_ops;
    extern int force_iommu, no_iommu;
    extern int iommu_detected;
    +extern int dmar_disabled;

    extern unsigned long iommu_num_pages(unsigned long addr, unsigned long len);

    --
    1.5.5.1
    --
    David Woodhouse Open Source Technology Centre
    David.Woodhouse@intel.com Intel Corporation




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