There is a lot of historical baggage on this parameter. It is defined in the vgacon driver as nomodeset, but its set function is called text_mode() and the value queried with a function named vgacon_text_force().
All this implies that it's about forcing text mode for VGA, yet it is not used in neither vgacon nor other console driver. The only users for these are DRM drivers, that check for the vgacon_text_force() return value to determine whether the driver should be loaded or not.
That makes it quite confusing to read the code, because the variables and function names don't reflect what they actually do and also are not in the same subsystem as the drivers that make use of them.
This patch-set attempts to cleanup the code by moving the nomodseset param to the DRM subsystem and do some renaming to make their intention clearer.
This is a v5 of the patches, that just renames the function used by drivers to check to drm_firmware_drivers_only(). Other than that is the same as v4.
Patch #1 and #2 are just trivial cleanups.
Patch #3 moves the nomodeset boot option to the DRM subsystem and renames the variables and functions names.
Patch #4 removes the relationship between the nomodeset parameter and the CONFIG_VGA_CONSOLE Kconfig symbol.
Patch #5 adds nomodeset to the kernel parameters documentation.
Patch #6 improves the message when nomodeset is enabled to make it more accurate and less sensational.
Changes in v5: - Rename drm_get_modeset() to drm_firmware_drivers_only().
Changes in v4: - Don't mention the simpledrm driver and instead explain in high level terms what the nomodeset option is about. - Don't mention DRM drivers in the kernel message and instead explain that only the system framebuffer will be available.
Changes in v3: - Drop the drm_drv_enabled() function and just call to drm_get_modeset(). - Make drm_get_modeset() just a getter function and don't return an error. - Move independent cleanups in drivers as separate preparatory patches.
Changes in v2: - Conditionally build drm_nomodeset.o if CONFIG_VGA_CONSOLE is set. - Squash patches to move nomodeset logic to DRM and do the renaming. - Name the function drm_check_modeset() and make it return -ENODEV. - Squash patch to add drm_drv_enabled() and make drivers use it. - Make the drivers changes before moving nomodeset logic to DRM. - Make drm_drv_enabled() return an errno and -ENODEV if nomodeset. - Remove debug and error messages in drivers.
Javier Martinez Canillas (6): drm: Don't print messages if drivers are disabled due nomodeset drm/vboxvideo: Drop CONFIG_VGA_CONSOLE guard to call vgacon_text_force() drm: Move nomodeset kernel parameter to the DRM subsystem drm: Decouple nomodeset from CONFIG_VGA_CONSOLE Documentation/admin-guide: Document nomodeset kernel parameter drm: Make the nomodeset message less sensational
.../admin-guide/kernel-parameters.txt | 7 ++++++ drivers/gpu/drm/Kconfig | 6 +++++ drivers/gpu/drm/Makefile | 2 ++ drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 5 +--- drivers/gpu/drm/ast/ast_drv.c | 3 +-- drivers/gpu/drm/drm_nomodeset.c | 24 +++++++++++++++++++ drivers/gpu/drm/i915/i915_module.c | 4 ++-- drivers/gpu/drm/mgag200/mgag200_drv.c | 3 +-- drivers/gpu/drm/nouveau/nouveau_drm.c | 4 ++-- drivers/gpu/drm/qxl/qxl_drv.c | 3 +-- drivers/gpu/drm/radeon/radeon_drv.c | 9 ++----- drivers/gpu/drm/tiny/bochs.c | 3 +-- drivers/gpu/drm/tiny/cirrus.c | 4 ++-- drivers/gpu/drm/vboxvideo/vbox_drv.c | 5 +--- drivers/gpu/drm/virtio/virtgpu_drv.c | 3 +-- drivers/gpu/drm/vmwgfx/vmwgfx_drv.c | 3 +-- drivers/video/console/vgacon.c | 21 ---------------- include/drm/drm_drv.h | 1 + include/linux/console.h | 6 ----- 19 files changed, 56 insertions(+), 60 deletions(-) create mode 100644 drivers/gpu/drm/drm_nomodeset.c