linux-kernel - Re: [PATCH v9 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

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Date:   Mon, 27 Aug 2018 08:56:50 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     gary.hook@....com
Cc:     Linux IOMMU <iommu@...ts.linux-foundation.org>,
        Joerg Roedel <joro@...tes.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        linux-kbuild <linux-kbuild@...r.kernel.org>
Subject: Re: [PATCH v9 2/2] iommu/amd: Add basic debugfs infrastructure for
 AMD IOMMU

Hi Gary,

On Tue, Jun 12, 2018 at 11:42 PM Gary R Hook <gary.hook@....com> wrote:
> Implement a skeleton framework for debugfs support in the AMD
> IOMMU.  Add an AMD-specific Kconfig boolean that depends upon
> general enablement of DebugFS in the IOMMU.
>
> Signed-off-by: Gary R Hook <gary.hook@....com>

This is now commit 7d0f5fd3e4d68742 ("iommu/amd: Add basic debugfs
infrastructure for AMD IOMMU").

> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -146,6 +146,18 @@ config AMD_IOMMU_V2
>           hardware. Select this option if you want to use devices that support
>           the PCI PRI and PASID interface.
>
> +config AMD_IOMMU_DEBUGFS
> +       bool "Enable AMD IOMMU internals in DebugFS"
> +       depends on AMD_IOMMU && IOMMU_DEBUGFS
> +       ---help---
> +         !!!WARNING!!!  !!!WARNING!!!  !!!WARNING!!!  !!!WARNING!!!
> +
> +         DO NOT ENABLE THIS OPTION UNLESS YOU REALLY, -REALLY- KNOW WHAT YOU ARE DOING!!!
> +         Exposes AMD IOMMU device internals in DebugFS.
> +
> +         This option is -NOT- intended for production environments, and should
> +         not generally be enabled.

If it is that bad, shouldn't this option be protected by some Kconfig
trickery to avoid it being enabled in allmodconfig/allyesconfig builds?

I forgot the way to do that, so some CCs added.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds