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How about removing this bool? Only > > > less than 10 lines of code are impacted and are not in any performance > > > path. > > > > > > diff --git a/drivers/iommu/intel/Kconfig b/drivers/iommu/intel/Kconfig > > > index b7dff5092fd2..5e077d1c5f5d 100644 > > > --- a/drivers/iommu/intel/Kconfig > > > +++ b/drivers/iommu/intel/Kconfig > > > @@ -75,15 +75,6 @@ config INTEL_IOMMU_BROKEN_GFX_WA > > >         to use physical addresses for DMA, at least until this > > >         option is removed in the 2.6.32 kernel. > > > > > > -config INTEL_IOMMU_FLOPPY_WA > > > -    def_bool y > > > -    depends on X86 > > > -    help > > > -      Floppy disk drivers are known to bypass DMA API calls > > > -      thereby failing to work when IOMMU is enabled. This > > > -      workaround will setup a 1:1 mapping for the first > > > -      16MiB to make floppy (an ISA device) work. > > > - > > >   config INTEL_IOMMU_SCALABLE_MODE_DEFAULT_ON > > >       bool "Enable Intel IOMMU scalable mode by default" > > >       default y > > > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c > > > index 48cdcd0a5cf3..22801850f339 100644 > > > --- a/drivers/iommu/intel/iommu.c > > > +++ b/drivers/iommu/intel/iommu.c > > > @@ -4567,7 +4567,6 @@ static void > > > intel_iommu_get_resv_regions(struct device *device, > > >       } > > >       rcu_read_unlock(); > > > > > > -#ifdef CONFIG_INTEL_IOMMU_FLOPPY_WA > > >       if (dev_is_pci(device)) { > > >           struct pci_dev *pdev = to_pci_dev(device); > > > > > > @@ -4579,7 +4578,6 @@ static void > > > intel_iommu_get_resv_regions(struct device *device, > > >                   list_add_tail(®->list, head); > > >           } > > >       } > > > -#endif /* CONFIG_INTEL_IOMMU_FLOPPY_WA */ > > > > > >       reg = iommu_alloc_resv_region(IOAPIC_RANGE_START, > > >                         IOAPIC_RANGE_END - IOAPIC_RANGE_START + 1, > > > > > > > Hi Baolu, > > > > I have a question: > > Shouldn't we remove the code between ifdef-endif statements? > > > > I mean something like this: > > > > diff --git a/drivers/iommu/intel/Kconfig b/drivers/iommu/intel/Kconfig > > index b7dff5092fd2..5e077d1c5f5d 100644 > > --- a/drivers/iommu/intel/Kconfig > > +++ b/drivers/iommu/intel/Kconfig > > @@ -75,15 +75,6 @@ config INTEL_IOMMU_BROKEN_GFX_WA > >           to use physical addresses for DMA, at least until this > >           option is removed in the 2.6.32 kernel. > > > > -config INTEL_IOMMU_FLOPPY_WA > > -       def_bool y > > -       depends on X86 > > -       help > > -         Floppy disk drivers are known to bypass DMA API calls > > -         thereby failing to work when IOMMU is enabled. This > > -         workaround will setup a 1:1 mapping for the first > > -         16MiB to make floppy (an ISA device) work. > > - > >  config INTEL_IOMMU_SCALABLE_MODE_DEFAULT_ON > >         bool "Enable Intel IOMMU scalable mode by default" > >         default y > > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c > > index 48cdcd0a5cf3..2c416ad3204e 100644 > > --- a/drivers/iommu/intel/iommu.c > > +++ b/drivers/iommu/intel/iommu.c > > @@ -4567,20 +4567,6 @@ static void intel_iommu_get_resv_regions(struct > > device *device, > >         } > >         rcu_read_unlock(); > > > > -#ifdef CONFIG_INTEL_IOMMU_FLOPPY_WA > > -       if (dev_is_pci(device)) { > > -               struct pci_dev *pdev = to_pci_dev(device); > > - > > -               if ((pdev->class >> 8) == PCI_CLASS_BRIDGE_ISA) { > > -                       reg = iommu_alloc_resv_region(0, 1UL << 24, prot, > > -                                       IOMMU_RESV_DIRECT_RELAXABLE, > > -                                       GFP_KERNEL); > > -                       if (reg) > > -                               list_add_tail(®->list, head); > > -               } > > -       } > > -#endif /* CONFIG_INTEL_IOMMU_FLOPPY_WA */ > > - > >         reg = iommu_alloc_resv_region(IOAPIC_RANGE_START, > >                                       IOAPIC_RANGE_END - > > IOAPIC_RANGE_START + 1, > >                                       0, IOMMU_RESV_MSI, GFP_KERNEL); > > > > This code is introduced in Commit d850c2ee5fe2 ("iommu/vt-d: Expose ISA > > direct mapping region via iommu_get_resv_regions") > > As long as floppy driver exists in the tree, we have to include above > code. Otherwise, floppy drivers don't work. At least we can easily find > drivers/block/floppy.c which is still maintained (check MAINTAINERS).:-) But this requires a machine with Intel IOMMU and ISA: > > > -      16MiB to make floppy (an ISA device) work. ISA device? I don't believe there are any Intel machines with an IOMMU and an ISA device?