Re: [PATCH 2/2] iommufd_driver: make IOMMUFD_DRIVER_CORE a 'bool' symbol

[Nicolin Chen <nicolinc@nvidia.com>]

On Mon, Mar 24, 2025 at 10:03:23PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> Calling iommufd_sw_msi() from iommu_dma_prepare_msi() in the iommu core
> code is no longer possible if the driver core is in a loadable module
> because it is now a direct call rather than a function pointer:
> 
> arm-linux-gnueabi-ld: drivers/iommu/iommu.o: in function `iommu_dma_prepare_msi':
> iommu.c:(.text+0x4fb4): undefined reference to `iommufd_sw_msi'
> 
> This effectively makes the iommu driver core part of the iommu subsystem
> itself, so disallow building it as a loadable module.
> 
> Fixes: e009e088d88e ("iommu: Drop sw_msi from iommu_domain")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  drivers/iommu/iommufd/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/iommufd/Kconfig b/drivers/iommu/iommufd/Kconfig
> index 0a07f9449fd9..2beeb4f60ee5 100644
> --- a/drivers/iommu/iommufd/Kconfig
> +++ b/drivers/iommu/iommufd/Kconfig
> @@ -1,6 +1,6 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  config IOMMUFD_DRIVER_CORE
> -	tristate
> +	bool

Hmm, looks like giving up this "tristate" is the only option as
IOMMU_API is now accessing iommufd_sw_msi() that itself and two
functions are kind of too big to be placed in a header.

Tested-by: Nicolin Chen <nicolinc@nvidia.com>

Thanks!