Re: [PATCH 04/16] drm/xe: Require CONFIGFS_FS

["Summers, Stuart" <stuart.summers@intel.com>]

On Fri, 2026-09-25 at 16:16 -0700, Matt Roper wrote:
> On Thu, Sep 24, 2026 at 11:01:23PM +0000, Stuart Summers wrote:
> > configfs is not optional for xe in practice: a growing set of
> > device
> 
> I'm not sure I agree with this claim; the Xe driver is certainly
> usable
> today without configfs and most users will never have any need to use
> it
> (and most are probably unaware of its existence).  Having configfs
> will
> give you a small number of additional features for certain corner
> cases
> (such as survivability mode), and those capabilities might be crucial
> to
> specific users, but they're not mandatory for general use of the
> driver
> or hardwawre.  In fact even features like survivability mode are only
> relevant on a specific subset of the platforms supported by Xe.  I'm
> not
> sure if there's any end-user use case for configfs today on igpu
> platforms for example.
> 
> I believe most distribution kernels do include configfs support
> today,
> so this support will usually be there if general users need it.  But
> if
> someone makes a conscious decision that they want a very small kernel
> and they feel they don't need any of the extra features offered by
> configfs, then that's really their call to make.  There are a lot of
> embedded system use cases where something like configfs just isn't
> going
> to be useful because you can't get at it anyway through the
> interfaces
> the device makes available, and including unnecessary facilities like
> configfs can interfere with certification requirements, timing
> requirements, etc.

Hm.. yeah I understand what you're saying and it's a good point. I was
hoping we could get rid of the dangling code here, but maybe it's
better to keep it for those use cases. I can drop this next rev.

Thanks,
Stuart

> 
> 
> Matt
> 
> > settings is only reachable through it, and the !CONFIGFS_FS stubs
> > silently return defaults instead, so those builds quietly ignore
> > every
> > configfs knob. Select it and drop the stubs rather than keep
> > growing a
> > second, no-op copy of the getter API.
> > 
> > Signed-off-by: Stuart Summers <stuart.summers@intel.com>
> > Assisted-by: Copilot:claude-opus-5
> > ---
> >  drivers/gpu/drm/xe/Kconfig       |  1 +
> >  drivers/gpu/drm/xe/Makefile      |  2 +-
> >  drivers/gpu/drm/xe/xe_configfs.h | 32 ----------------------------
> > ----
> >  3 files changed, 2 insertions(+), 33 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/xe/Kconfig
> > b/drivers/gpu/drm/xe/Kconfig
> > index 4d7dcaff2b91..a24b5e574699 100644
> > --- a/drivers/gpu/drm/xe/Kconfig
> > +++ b/drivers/gpu/drm/xe/Kconfig
> > @@ -6,6 +6,7 @@ config DRM_XE
> >         depends on INTEL_VSEC || !INTEL_VSEC
> >         depends on X86_PLATFORM_DEVICES || !(X86 && ACPI)
> >         depends on PAGE_SIZE_4KB || COMPILE_TEST || BROKEN
> > +       select CONFIGFS_FS
> >         select INTERVAL_TREE
> >         # we need shmfs for the swappable backing store, and in
> > particular
> >         # the shmem_readpage() which depends upon tmpfs
> > diff --git a/drivers/gpu/drm/xe/Makefile
> > b/drivers/gpu/drm/xe/Makefile
> > index ba4404896f2f..aa5d6184713b 100644
> > --- a/drivers/gpu/drm/xe/Makefile
> > +++ b/drivers/gpu/drm/xe/Makefile
> > @@ -164,7 +164,7 @@ xe-$(CONFIG_DRM_GPUSVM) += xe_userptr.o
> >  xe-$(CONFIG_HWMON) += xe_hwmon.o
> >  
> >  xe-$(CONFIG_PERF_EVENTS) += xe_pmu.o
> > -xe-$(CONFIG_CONFIGFS_FS) += xe_configfs.o
> > +xe-y += xe_configfs.o
> >  
> >  # graphics virtualization (SR-IOV) support
> >  xe-y += \
> > diff --git a/drivers/gpu/drm/xe/xe_configfs.h
> > b/drivers/gpu/drm/xe/xe_configfs.h
> > index f89dc0ffb884..ff902d7488ca 100644
> > --- a/drivers/gpu/drm/xe/xe_configfs.h
> > +++ b/drivers/gpu/drm/xe/xe_configfs.h
> > @@ -5,16 +5,12 @@
> >  #ifndef _XE_CONFIGFS_H_
> >  #define _XE_CONFIGFS_H_
> >  
> > -#include <linux/limits.h>
> >  #include <linux/types.h>
> >  
> > -#include "xe_defaults.h"
> >  #include "xe_hw_engine_types.h"
> > -#include "xe_module.h"
> >  
> >  struct pci_dev;
> >  
> > -#if IS_ENABLED(CONFIG_CONFIGFS_FS)
> >  int xe_configfs_init(void);
> >  void xe_configfs_exit(void);
> >  void xe_configfs_check_device(struct pci_dev *pdev);
> > @@ -35,33 +31,5 @@ ssize_t
> > xe_configfs_get_ctx_restore_post_bb(struct pci_dev *pdev,
> >  unsigned int xe_configfs_get_max_vfs(struct pci_dev *pdev);
> >  bool xe_configfs_admin_only_pf(struct pci_dev *pdev);
> >  #endif
> > -#else
> > -static inline int xe_configfs_init(void) { return 0; }
> > -static inline void xe_configfs_exit(void) { }
> > -static inline void xe_configfs_check_device(struct pci_dev *pdev)
> > { }
> > -static inline bool xe_configfs_get_survivability_mode(struct
> > pci_dev *pdev) { return false; }
> > -static inline bool xe_configfs_primary_gt_allowed(struct pci_dev
> > *pdev) { return true; }
> > -static inline bool xe_configfs_media_gt_allowed(struct pci_dev
> > *pdev) { return true; }
> > -static inline u64 xe_configfs_get_engines_allowed(struct pci_dev
> > *pdev) { return U64_MAX; }
> > -static inline bool xe_configfs_get_psmi_enabled(struct pci_dev
> > *pdev) { return false; }
> > -static inline bool xe_configfs_get_enable_multi_queue(struct
> > pci_dev *pdev) { return true; }
> > -static inline bool
> > xe_configfs_get_disable_vram_page_offline(struct pci_dev *pdev) {
> > return false; }
> > -static inline ssize_t xe_configfs_get_ctx_restore_mid_bb(struct
> > pci_dev *pdev,
> > -                                                        enum
> > xe_engine_class class,
> > -                                                        u32 *cs,
> > size_t max_len) { return 0; }
> > -static inline ssize_t xe_configfs_get_ctx_restore_post_bb(struct
> > pci_dev *pdev,
> > -                                                         enum
> > xe_engine_class class,
> > -                                                         u32 *cs,
> > size_t max_len) { return 0; }
> > -#ifdef CONFIG_PCI_IOV
> > -static inline unsigned int xe_configfs_get_max_vfs(struct pci_dev
> > *pdev)
> > -{
> > -       return xe_modparam.max_vfs;
> > -}
> > -static inline bool xe_configfs_admin_only_pf(struct pci_dev *pdev)
> > -{
> > -       return XE_DEFAULT_ADMIN_ONLY_PF;
> > -}
> > -#endif
> > -#endif
> >  
> >  #endif
> > -- 
> > 2.43.0
> > 
>