On Tue, Aug 07, 2012 at 03:48:09PM -0500, Seth Forshee wrote:
> The ACPI tables in the Macbook Air 5,1 define a single IOAPIC with id 2,
> but the only remapping unit described in the DMAR table matches id 0.
> Interrupt remapping fails as a result, and the kernel panics with the
> message "timer doesn't work through Interrupt-remapped IO-APIC."
>
> To fix this, check each IOAPIC for a corresponding IOMMU. If an IOMMU is
> not found, do not allow IRQ remapping to be enabled.
>
> Signed-off-by: Seth Forshee <[email protected]>
> ---
> drivers/iommu/intel_irq_remapping.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/drivers/iommu/intel_irq_remapping.c
> b/drivers/iommu/intel_irq_remapping.c
> index e0b18f3..ce2c0c6 100644
> --- a/drivers/iommu/intel_irq_remapping.c
> +++ b/drivers/iommu/intel_irq_remapping.c
> @@ -526,6 +526,7 @@ static int __init intel_irq_remapping_supported(void)
> static int __init intel_enable_irq_remapping(void)
> {
> struct dmar_drhd_unit *drhd;
> + int ioapic_idx;
> int setup = 0;
> int eim = 0;
>
> @@ -534,6 +535,16 @@ static int __init intel_enable_irq_remapping(void)
> return -1;
> }
>
> + for (ioapic_idx = 0; ioapic_idx < nr_ioapics; ioapic_idx++) {
> + int ioapic_id = mpc_ioapic_id(ioapic_idx);
> + if (!map_ioapic_to_ir(ioapic_id)) {
> + pr_info("ioapic %d has no mapping iommu, "
> + "interrupt remapping will be disabled\n",
> + ioapic_id);
> + return -1;
> + }
> + }
> +
I would change this to pr_err() and add FW_BUG to make clear that this
is an error caused by a firmware bug.
Joerg
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