Re: [PATCH v8 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

From: Gary R Hook
Date: Tue Jun 12 2018 - 14:40:28 EST

On 06/04/2018 08:23 PM, Randy Dunlap wrote:
On 05/29/2018 11:39 AM, Greg KH wrote:
On Tue, May 29, 2018 at 01:23:23PM -0500, Gary R Hook wrote:
Implement a skeleton framework for debugfs support in the
AMD IOMMU. Add a hidden boolean to Kconfig that is defined
for the AMD IOMMU when general IOMMY DebugFS support is

Signed-off-by: Gary R Hook <gary.hook@xxxxxxx>
drivers/iommu/Kconfig | 4 ++++
drivers/iommu/Makefile | 1 +
drivers/iommu/amd_iommu_debugfs.c | 39 +++++++++++++++++++++++++++++++++++++
drivers/iommu/amd_iommu_init.c | 6 ++++--
drivers/iommu/amd_iommu_proto.h | 6 ++++++
drivers/iommu/amd_iommu_types.h | 5 +++++
6 files changed, 59 insertions(+), 2 deletions(-)
create mode 100644 drivers/iommu/amd_iommu_debugfs.c

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index f9af25ac409f..ec223f6f4ad4 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -137,6 +137,10 @@ config AMD_IOMMU
your BIOS for an option to enable it or if you have an IVRS ACPI
+ def_bool y

Why default y? Can you not boot a box without this? If not, it should
not be Y.

config AMD_IOMMU_V2
tristate "AMD IOMMU Version 2 driver"
depends on AMD_IOMMU


By far, most driver-debugfs additions are optional and include a user Kconfig prompt
so that user's can choose whether to enable it or not.

I suggest that the way forward is to fix Greg's debugfs_() api comments
and to add a prompt string to AMD_IOMMU_DEBUGFS.

Roger. I think we have that all worked out. Will send another version soon.