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

[Lu Baolu]

Hi Robin,

On 6/18/21 2:56 AM, Robin Murphy wrote:
> > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> > > index 60b1ec42e73b..ff221d3ddcbc 100644
> > > --- a/drivers/iommu/iommu.c
> > > +++ b/drivers/iommu/iommu.c
> > > @@ -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);
>
> Note that this is the bit that does the real work - if the argument 
> parses OK then iommu_dma_strict is reassigned with the appropriate 
> value. The iommu_cmd_line stuff is a bit of additional bookkeeping, 
> basically just so we can see whether default values have been overridden.

Ah, get it. Thanks a lot. I missed this part and naively thought it just
converts a string to integer.

Best regards,
baolu