Re: [Xen-devel] [PATCH v2] iommu: leave IOMMU enabled by default during kexec crash transition

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 21.02.19 at 23:08, <igor.druzhinin@xxxxxxxxxx> wrote:
> Modern Linux kernels taught to copy all the necessary DMAR/IR tables
> following kexec from the previous kernel (Xen in our case) - so it's
> currently normal to keep IOMMU enabled. It might require minor changes to
> kdump command line that enables IOMMU drivers (e.g. intel_iommu=on /
> intremap=on) but recent kernels don't require any additional changes for
> the transition to be transparent.

In your reply on the v1 thread didn't you say Linux disables translation?

> --- a/xen/drivers/passthrough/iommu.c
> +++ b/xen/drivers/passthrough/iommu.c
> @@ -35,6 +35,7 @@ bool_t __read_mostly iommu_igfx = 1;
>  bool_t __read_mostly iommu_snoop = 1;
>  bool_t __read_mostly iommu_qinval = 1;
>  bool_t __read_mostly iommu_intremap = 1;
> +bool_t __read_mostly iommu_crash_disable;
>  
>  static bool __hwdom_initdata iommu_hwdom_none;
>  bool __hwdom_initdata iommu_hwdom_strict;

While I can see that all upper context still uses bool_t, lower context
already suggests to better use bool. An easy to make adjustment
while committing if no other need arises for a v3.

Jan



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