Re: [PATCH] iommu: Print default strict or lazy mode at init time

[John Garry]

On 01/06/2021 10:09, Robin Murphy wrote:
> > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> > index 808ab70d5df5..f25fae62f077 100644
> > --- a/drivers/iommu/iommu.c
> > +++ b/drivers/iommu/iommu.c
> > @@ -138,6 +138,11 @@ static int __init iommu_subsys_init(void)
> >           (iommu_cmd_line & IOMMU_CMD_LINE_DMA_API) ?
> >               "(set via kernel command line)" : "");
> > +    pr_info("Default DMA domain mode: %s %s\n",
>
> Nit: I think this might be a little unclear for end-users - *I'm* not 
> even sure whether "Default" here is meant to refer to the mode setting 
> itself or to default domains (of DMA type). Maybe something like "DMA 
> domain TLB invalidation policy"? Certainly it seems like a good idea to 
> explicitly mention invalidation to correlate with the documentation of 
> the "iommu.strict" parameter.
>
> Ack to the general idea though.

ok, so I'll go with this:

pr_info("DMA domain default TLB invalidation policy: %s mode %s\n",
              iommu_dma_strict ? "strict" : "lazy",
               (iommu_cmd_line & IOMMU_CMD_LINE_STRICT) ?
                       "(set via kernel command line)" : "");

I think it's worth mentioning "default" somewhere, as not all IOMMUs or 
devices will use lazy mode even if it's default.

Thanks,
John