Re: [PATCH v13 6/6] iommu: Remove mode argument from iommu_set_dma_strict()

[John Garry]

> > @@ -349,10 +349,9 @@ static int __init iommu_dma_setup(char *str)
> >   }
> >   early_param("iommu.strict", iommu_dma_setup);
> > -void iommu_set_dma_strict(bool strict)
> > +void iommu_set_dma_strict(void)
> >   {
> > -    if (strict || !(iommu_cmd_line & IOMMU_CMD_LINE_STRICT))
> > -        iommu_dma_strict = strict;
> > +    iommu_dma_strict = true;
>
> Sorry, I still can't get how iommu.strict kernel option works.
>
> static int __init iommu_dma_setup(char *str)
> {
>          int ret = kstrtobool(str, &iommu_dma_strict);
>
>          if (!ret)
>                  iommu_cmd_line |= IOMMU_CMD_LINE_STRICT;
>          return ret;
> }
> early_param("iommu.strict", iommu_dma_setup);
>
> The bit IOMMU_CMD_LINE_STRICT is only set, but not used anywhere.

It is used in patch 2/6:

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

> Hence,
> I am wondering how could it work? A bug or I missed anything?

It is really just used for informative purpose now.

Thanks,
john