Re: [PATCH v7 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

[Gary R Hook]

On 05/18/2018 11:49 AM, Randy Dunlap wrote:
> On 05/18/2018 08:20 AM, Gary R Hook wrote:
> > On 05/15/2018 08:46 AM, Joerg Roedel wrote:
> > > On Mon, May 14, 2018 at 03:00:50PM -0500, Gary R Hook wrote:
> > > > This was brought up a few weeks ago in, I believe, version 3 of this patch.
> > > > That question was discussed (because that's what I did the first time out),
> > > > and _someone_ _else_ asked about why I didn't just do it the way I've done
> > > > it here.
> > >
> > > You don't have this problem if you put the code in amd_iommu.c in an
> > > IOMMU_DEBUGFS ifdef.
> >
> > Of course. My preference, however, is a separate file to avoid size creep. That's why I've done it this way.
> >
> > To whit: there have been threads discussing the advisability/acceptability of using #ifdefs for debug code. My take-away was to avoid them. Perhaps I misunderstood.
> >
> > So: I don't understand your comment. Is this an observation, or is it an imperative statement? I'd like for a maintainer to clearly indicate what is acceptable, and I'll do it.
>
> Hi,
> I looked back at Robin Murphy's comments on April 17:
>
> <quote>
> Well, you could do a makefile-level dependency i.e.:
>
> ifeq ($(CONFIG_IOMMU_DEBUG), y)
> obj-$(CONFIG_AMD_IOMMU) += amd_iommu_debugfs.o
> obj-$(CONFIG_BLAH_IOMMU) += blah_iommu_debugfs.o
> ...
> endif
>
> Or alternatively have an intermediate silent Kconfig option:
>
> config AMD_IOMMU_DEBUG
> 	def_bool y
> 	depends on AMD_IOMMU && IOMMU_DEBUG
>
> The makefile option is arguably ugly, but does at least scale better ;)
> </quote>
>
>
> I think the Kconfig option would have been the correct choice.

"Preferred", perhaps. Neither is incorrect. And really, the 
Makefile/Kconfig choice is somewhat separate from the organization issue.

So I've made the changes for this. Now I'm waiting on Joerg to make a 
decision on the code/file organization. I still prefer a separate file 
for the debug fs code.