On 2023-07-24 17:14, Michał Winiarski
wrote:
Having a limit of 64 DRM devices is not good enough for modern world where we have multi-GPU servers, SR-IOV virtual functions and virtual devices used for testing. Let's utilize full minor range for DRM devices. To avoid regressing the existing userspace, we're still maintaining the numbering scheme where 0-63 is used for primary, 64-127 is reserved (formerly for control) and 128-191 is used for render. For minors >= 192, we're allocating minors dynamically on a first-come, first-served basis.
[JZ] Hello Michal,
Do you have libdrm patches for review together with this change?
Especially to support static int drmGetMinorType(int major, int minor).
Thanks and Best Regards!
James Zhu
Signed-off-by: Michał Winiarski <michal.winiarski@xxxxxxxxx> --- drivers/gpu/drm/drm_drv.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c index 34b60196c443..c2c6e80e6b31 100644 --- a/drivers/gpu/drm/drm_drv.c +++ b/drivers/gpu/drm/drm_drv.c @@ -121,10 +121,19 @@ static void drm_minor_alloc_release(struct drm_device *dev, void *data) xa_erase(drm_minor_get_xa(minor->type), minor->index); } +/* + * DRM used to support 64 devices, for backwards compatibility we need to maintain the + * minor allocation scheme where minors 0-63 are primary nodes, 64-127 are control nodes, + * and 128-191 are render nodes. + * After reaching the limit, we're allocating minors dynamically - first-come, first-serve. + * Accel nodes are using a distinct major, so the minors are allocated in continuous 0-MAX + * range. + */ #define DRM_MINOR_LIMIT(t) ({ \ typeof(t) _t = (t); \ _t == DRM_MINOR_ACCEL ? XA_LIMIT(0, ACCEL_MAX_MINORS) : XA_LIMIT(64 * _t, 64 * _t + 63); \ }) +#define DRM_EXTENDED_MINOR_LIMIT XA_LIMIT(192, (1 << MINORBITS) - 1) static int drm_minor_alloc(struct drm_device *dev, enum drm_minor_type type) { @@ -140,6 +149,9 @@ static int drm_minor_alloc(struct drm_device *dev, enum drm_minor_type type) r = xa_alloc(drm_minor_get_xa(type), &minor->index, NULL, DRM_MINOR_LIMIT(type), GFP_KERNEL); + if (r == -EBUSY && (type == DRM_MINOR_PRIMARY || type == DRM_MINOR_RENDER)) + r = xa_alloc(&drm_minors_xa, &minor->index, + NULL, DRM_EXTENDED_MINOR_LIMIT, GFP_KERNEL); if (r < 0) return r;
