Re: [PATCH] [v2] PCI: add CONFIG_MMU dependency

[Bjorn Helgaas <helgaas@kernel.org>]

On Wed, Apr 23, 2025 at 10:16:32PM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> It turns out that there are no platforms that have PCI but don't have an MMU,
> so adding a Kconfig dependency on CONFIG_PCI simplifies build testing kernels
> for those platforms a lot, and avoids a lot of inadvertent build regressions.
> 
> Add a dependency for CONFIG_PCI and remove all the ones for PCI specific
> device drivers that are currently marked not having it.
> 
> There are a few platforms that have an optional MMU, but they usually cannot
> have PCI at all. The one exception is Coldfire MCF54xx, but this is mainly
> for historic reasons, and anyone using those chips should really use the
> MMU these days.
> 
> Link: https://lore.kernel.org/lkml/a41f1b20-a76c-43d8-8c36-f12744327a54@app.fastmail.com/
> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> # SCSI
> Acked-by: Alex Deucher <alexander.deucher@amd.com>
> Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> v2: update changelog text
> 
> Bjorn, can you take this through the PCI tree? I thought about splitting
> it up by subsystem, but it's really one thing that I'm doing here, and
> doing it in one bit makes more sense to me.

Applied to pci/misc for v6.16, thanks!

The PCI tree is based on -rc1, so there were a few minor merge
conflicts, but they're obvious.

> ---
>  drivers/accel/qaic/Kconfig              | 1 -
>  drivers/firewire/Kconfig                | 2 +-
>  drivers/gpu/drm/Kconfig                 | 2 +-
>  drivers/gpu/drm/amd/amdgpu/Kconfig      | 3 +--
>  drivers/gpu/drm/ast/Kconfig             | 2 +-
>  drivers/gpu/drm/gma500/Kconfig          | 2 +-
>  drivers/gpu/drm/hisilicon/hibmc/Kconfig | 1 -
>  drivers/gpu/drm/loongson/Kconfig        | 2 +-
>  drivers/gpu/drm/mgag200/Kconfig         | 2 +-
>  drivers/gpu/drm/nouveau/Kconfig         | 3 +--
>  drivers/gpu/drm/qxl/Kconfig             | 2 +-
>  drivers/gpu/drm/radeon/Kconfig          | 2 +-
>  drivers/gpu/drm/tiny/Kconfig            | 2 +-
>  drivers/gpu/drm/vmwgfx/Kconfig          | 2 +-
>  drivers/gpu/drm/xe/Kconfig              | 2 +-
>  drivers/net/ethernet/broadcom/Kconfig   | 1 -
>  drivers/pci/Kconfig                     | 1 +
>  drivers/pci/pci.c                       | 4 ++--
>  drivers/scsi/bnx2fc/Kconfig             | 1 -
>  drivers/scsi/bnx2i/Kconfig              | 1 -
>  drivers/vfio/pci/Kconfig                | 2 +-
>  21 files changed, 17 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/accel/qaic/Kconfig b/drivers/accel/qaic/Kconfig
> index a9f866230058..5e405a19c157 100644
> --- a/drivers/accel/qaic/Kconfig
> +++ b/drivers/accel/qaic/Kconfig
> @@ -8,7 +8,6 @@ config DRM_ACCEL_QAIC
>  	depends on DRM_ACCEL
>  	depends on PCI && HAS_IOMEM
>  	depends on MHI_BUS
> -	depends on MMU
>  	select CRC32
>  	help
>  	  Enables driver for Qualcomm's Cloud AI accelerator PCIe cards that are
> diff --git a/drivers/firewire/Kconfig b/drivers/firewire/Kconfig
> index 905c82e26ce7..a5f5e250223a 100644
> --- a/drivers/firewire/Kconfig
> +++ b/drivers/firewire/Kconfig
> @@ -83,7 +83,7 @@ config FIREWIRE_KUNIT_SELF_ID_SEQUENCE_HELPER_TEST
>  
>  config FIREWIRE_OHCI
>  	tristate "OHCI-1394 controllers"
> -	depends on PCI && FIREWIRE && MMU
> +	depends on PCI && FIREWIRE
>  	help
>  	  Enable this driver if you have a FireWire controller based
>  	  on the OHCI specification.  For all practical purposes, this
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index 89d00265d578..831bd384f1fd 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -393,7 +393,7 @@ source "drivers/gpu/drm/imagination/Kconfig"
>  
>  config DRM_HYPERV
>  	tristate "DRM Support for Hyper-V synthetic video device"
> -	depends on DRM && PCI && MMU && HYPERV
> +	depends on DRM && PCI && HYPERV
>  	select DRM_CLIENT_SELECTION
>  	select DRM_KMS_HELPER
>  	select DRM_GEM_SHMEM_HELPER
> diff --git a/drivers/gpu/drm/amd/amdgpu/Kconfig b/drivers/gpu/drm/amd/amdgpu/Kconfig
> index 7b95221d2f3d..64e603f971b8 100644
> --- a/drivers/gpu/drm/amd/amdgpu/Kconfig
> +++ b/drivers/gpu/drm/amd/amdgpu/Kconfig
> @@ -2,7 +2,7 @@
>  
>  config DRM_AMDGPU
>  	tristate "AMD GPU"
> -	depends on DRM && PCI && MMU
> +	depends on DRM && PCI
>  	depends on !UML
>  	select FW_LOADER
>  	select DRM_CLIENT
> @@ -68,7 +68,6 @@ config DRM_AMDGPU_CIK
>  config DRM_AMDGPU_USERPTR
>  	bool "Always enable userptr write support"
>  	depends on DRM_AMDGPU
> -	depends on MMU
>  	select HMM_MIRROR
>  	select MMU_NOTIFIER
>  	help
> diff --git a/drivers/gpu/drm/ast/Kconfig b/drivers/gpu/drm/ast/Kconfig
> index da0663542e8a..242fbccdf844 100644
> --- a/drivers/gpu/drm/ast/Kconfig
> +++ b/drivers/gpu/drm/ast/Kconfig
> @@ -1,7 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  config DRM_AST
>  	tristate "AST server chips"
> -	depends on DRM && PCI && MMU
> +	depends on DRM && PCI
>  	select DRM_CLIENT_SELECTION
>  	select DRM_GEM_SHMEM_HELPER
>  	select DRM_KMS_HELPER
> diff --git a/drivers/gpu/drm/gma500/Kconfig b/drivers/gpu/drm/gma500/Kconfig
> index 1613e51eff2d..e4c80e1a6da5 100644
> --- a/drivers/gpu/drm/gma500/Kconfig
> +++ b/drivers/gpu/drm/gma500/Kconfig
> @@ -1,7 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  config DRM_GMA500
>  	tristate "Intel GMA500/600/3600/3650 KMS Framebuffer"
> -	depends on DRM && PCI && X86 && MMU && HAS_IOPORT
> +	depends on DRM && PCI && X86 && HAS_IOPORT
>  	select DRM_CLIENT_SELECTION
>  	depends on ACPI_VIDEO || !ACPI
>  	depends on I2C
> diff --git a/drivers/gpu/drm/hisilicon/hibmc/Kconfig b/drivers/gpu/drm/hisilicon/hibmc/Kconfig
> index 98d77d74999d..d1f3f5793f34 100644
> --- a/drivers/gpu/drm/hisilicon/hibmc/Kconfig
> +++ b/drivers/gpu/drm/hisilicon/hibmc/Kconfig
> @@ -2,7 +2,6 @@
>  config DRM_HISI_HIBMC
>  	tristate "DRM Support for Hisilicon Hibmc"
>  	depends on DRM && PCI
> -	depends on MMU
>  	select DRM_CLIENT_SELECTION
>  	select DRM_DISPLAY_HELPER
>  	select DRM_DISPLAY_DP_HELPER
> diff --git a/drivers/gpu/drm/loongson/Kconfig b/drivers/gpu/drm/loongson/Kconfig
> index 552edfec7afb..d739d51cf54c 100644
> --- a/drivers/gpu/drm/loongson/Kconfig
> +++ b/drivers/gpu/drm/loongson/Kconfig
> @@ -2,7 +2,7 @@
>  
>  config DRM_LOONGSON
>  	tristate "DRM support for Loongson Graphics"
> -	depends on DRM && PCI && MMU
> +	depends on DRM && PCI
>  	depends on LOONGARCH || MIPS || COMPILE_TEST
>  	select DRM_CLIENT_SELECTION
>  	select DRM_KMS_HELPER
> diff --git a/drivers/gpu/drm/mgag200/Kconfig b/drivers/gpu/drm/mgag200/Kconfig
> index 412dcbea0e2d..a962ae564a75 100644
> --- a/drivers/gpu/drm/mgag200/Kconfig
> +++ b/drivers/gpu/drm/mgag200/Kconfig
> @@ -1,7 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  config DRM_MGAG200
>  	tristate "Matrox G200"
> -	depends on DRM && PCI && MMU
> +	depends on DRM && PCI
>  	select DRM_CLIENT_SELECTION
>  	select DRM_GEM_SHMEM_HELPER
>  	select DRM_KMS_HELPER
> diff --git a/drivers/gpu/drm/nouveau/Kconfig b/drivers/gpu/drm/nouveau/Kconfig
> index 9ba89b35d1a2..4fae780f7d78 100644
> --- a/drivers/gpu/drm/nouveau/Kconfig
> +++ b/drivers/gpu/drm/nouveau/Kconfig
> @@ -1,7 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  config DRM_NOUVEAU
>  	tristate "Nouveau (NVIDIA) cards"
> -	depends on DRM && PCI && MMU
> +	depends on DRM && PCI
>  	depends on (ACPI_VIDEO && ACPI_WMI && MXM_WMI) || !(ACPI && X86)
>  	depends on BACKLIGHT_CLASS_DEVICE
>  	select IOMMU_API
> @@ -86,7 +86,6 @@ config DRM_NOUVEAU_SVM
>  	bool "(EXPERIMENTAL) Enable SVM (Shared Virtual Memory) support"
>  	depends on DEVICE_PRIVATE
>  	depends on DRM_NOUVEAU
> -	depends on MMU
>  	depends on STAGING
>  	select HMM_MIRROR
>  	select MMU_NOTIFIER
> diff --git a/drivers/gpu/drm/qxl/Kconfig b/drivers/gpu/drm/qxl/Kconfig
> index 69427eb8bed2..d8f24bcae34b 100644
> --- a/drivers/gpu/drm/qxl/Kconfig
> +++ b/drivers/gpu/drm/qxl/Kconfig
> @@ -1,7 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  config DRM_QXL
>  	tristate "QXL virtual GPU"
> -	depends on DRM && PCI && MMU && HAS_IOPORT
> +	depends on DRM && PCI && HAS_IOPORT
>  	select DRM_CLIENT_SELECTION
>  	select DRM_KMS_HELPER
>  	select DRM_TTM
> diff --git a/drivers/gpu/drm/radeon/Kconfig b/drivers/gpu/drm/radeon/Kconfig
> index f51bace9555d..c479f0c0dd5c 100644
> --- a/drivers/gpu/drm/radeon/Kconfig
> +++ b/drivers/gpu/drm/radeon/Kconfig
> @@ -2,7 +2,7 @@
>  
>  config DRM_RADEON
>  	tristate "ATI Radeon"
> -	depends on DRM && PCI && MMU
> +	depends on DRM && PCI
>  	depends on AGP || !AGP
>  	select FW_LOADER
>  	select DRM_CLIENT_SELECTION
> diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig
> index 95c1457d7730..c50186a65464 100644
> --- a/drivers/gpu/drm/tiny/Kconfig
> +++ b/drivers/gpu/drm/tiny/Kconfig
> @@ -37,7 +37,7 @@ config DRM_BOCHS
>  
>  config DRM_CIRRUS_QEMU
>  	tristate "Cirrus driver for QEMU emulated device"
> -	depends on DRM && PCI && MMU
> +	depends on DRM && PCI
>  	select DRM_CLIENT_SELECTION
>  	select DRM_KMS_HELPER
>  	select DRM_GEM_SHMEM_HELPER
> diff --git a/drivers/gpu/drm/vmwgfx/Kconfig b/drivers/gpu/drm/vmwgfx/Kconfig
> index 6c3c2922ae8b..aab646b91ca9 100644
> --- a/drivers/gpu/drm/vmwgfx/Kconfig
> +++ b/drivers/gpu/drm/vmwgfx/Kconfig
> @@ -1,7 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0
>  config DRM_VMWGFX
>  	tristate "DRM driver for VMware Virtual GPU"
> -	depends on DRM && PCI && MMU
> +	depends on DRM && PCI
>  	depends on (X86 && HYPERVISOR_GUEST) || ARM64
>  	select DRM_CLIENT_SELECTION
>  	select DRM_TTM
> diff --git a/drivers/gpu/drm/xe/Kconfig b/drivers/gpu/drm/xe/Kconfig
> index dd256b355613..bb3f34a29f4e 100644
> --- a/drivers/gpu/drm/xe/Kconfig
> +++ b/drivers/gpu/drm/xe/Kconfig
> @@ -1,7 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  config DRM_XE
>  	tristate "Intel Xe Graphics"
> -	depends on DRM && PCI && MMU && (m || (y && KUNIT=y))
> +	depends on DRM && PCI && (m || (y && KUNIT=y))
>  	depends on INTEL_VSEC
>  	select INTERVAL_TREE
>  	# we need shmfs for the swappable backing store, and in particular
> diff --git a/drivers/net/ethernet/broadcom/Kconfig b/drivers/net/ethernet/broadcom/Kconfig
> index 46d07b81097f..1bcf406a9e36 100644
> --- a/drivers/net/ethernet/broadcom/Kconfig
> +++ b/drivers/net/ethernet/broadcom/Kconfig
> @@ -98,7 +98,6 @@ config BNX2
>  config CNIC
>  	tristate "QLogic CNIC support"
>  	depends on PCI && (IPV6 || IPV6=n)
> -	depends on MMU
>  	select BNX2
>  	select UIO
>  	help
> diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
> index da28295b4aac..9c0e4aaf4e8c 100644
> --- a/drivers/pci/Kconfig
> +++ b/drivers/pci/Kconfig
> @@ -21,6 +21,7 @@ config GENERIC_PCI_IOMAP
>  menuconfig PCI
>  	bool "PCI support"
>  	depends on HAVE_PCI
> +	depends on MMU
>  	help
>  	  This option enables support for the PCI local bus, including
>  	  support for PCI-X and the foundations for PCI Express support.
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 186858293df5..206f271e869a 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -4257,7 +4257,7 @@ unsigned long __weak pci_address_to_pio(phys_addr_t address)
>  #ifndef pci_remap_iospace
>  int pci_remap_iospace(const struct resource *res, phys_addr_t phys_addr)
>  {
> -#if defined(PCI_IOBASE) && defined(CONFIG_MMU)
> +#if defined(PCI_IOBASE)
>  	unsigned long vaddr = (unsigned long)PCI_IOBASE + res->start;
>  
>  	if (!(res->flags & IORESOURCE_IO))
> @@ -4290,7 +4290,7 @@ EXPORT_SYMBOL(pci_remap_iospace);
>   */
>  void pci_unmap_iospace(struct resource *res)
>  {
> -#if defined(PCI_IOBASE) && defined(CONFIG_MMU)
> +#if defined(PCI_IOBASE)
>  	unsigned long vaddr = (unsigned long)PCI_IOBASE + res->start;
>  
>  	vunmap_range(vaddr, vaddr + resource_size(res));
> diff --git a/drivers/scsi/bnx2fc/Kconfig b/drivers/scsi/bnx2fc/Kconfig
> index ecdc0f0f4f4e..3cf7e08df809 100644
> --- a/drivers/scsi/bnx2fc/Kconfig
> +++ b/drivers/scsi/bnx2fc/Kconfig
> @@ -5,7 +5,6 @@ config SCSI_BNX2X_FCOE
>  	depends on (IPV6 || IPV6=n)
>  	depends on LIBFC
>  	depends on LIBFCOE
> -	depends on MMU
>  	select NETDEVICES
>  	select ETHERNET
>  	select NET_VENDOR_BROADCOM
> diff --git a/drivers/scsi/bnx2i/Kconfig b/drivers/scsi/bnx2i/Kconfig
> index 0cc06c2ce0b8..75ace2302fed 100644
> --- a/drivers/scsi/bnx2i/Kconfig
> +++ b/drivers/scsi/bnx2i/Kconfig
> @@ -4,7 +4,6 @@ config SCSI_BNX2_ISCSI
>  	depends on NET
>  	depends on PCI
>  	depends on (IPV6 || IPV6=n)
> -	depends on MMU
>  	select SCSI_ISCSI_ATTRS
>  	select NETDEVICES
>  	select ETHERNET
> diff --git a/drivers/vfio/pci/Kconfig b/drivers/vfio/pci/Kconfig
> index c3bcb6911c53..2b0172f54665 100644
> --- a/drivers/vfio/pci/Kconfig
> +++ b/drivers/vfio/pci/Kconfig
> @@ -1,6 +1,6 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  menu "VFIO support for PCI devices"
> -	depends on PCI && MMU
> +	depends on PCI
>  
>  config VFIO_PCI_CORE
>  	tristate
> -- 
> 2.39.5
>