git: syscons - Use vtophys() for mmap-ing the framebuffer.

[Imre Vadasz]

commit f76e8b935cd9b27328877f9637a1d45dd9cdd045
Author: Imre Vadász <imre at vdsz.com>
Date:   Sun Jan 11 13:16:41 2026 +0100

    syscons - Use vtophys() for mmap-ing the framebuffer.
    
    With this change, the xf86-video-scrb Xorg/XLibre driver works reliably
    on machines using the amdgpu(4) KMS driver.
    
    With amdgpu(4), the framebuffer may be allocated from GTT memory (managed
    by TTM and accessed by the GPU through its own IOMMU), and hence is not
    contiguous in physical memory.
    Using vtophys() in the .d_mmap handler effectively determines the correct
    physical address one-by-one for each page of the framebuffer, based on the
    kernel's virtual memory mapping.
    
    More optimally, we would call into the correct drm/ttm function to handle
    these mmap requests in a more efficient way, however that will require some
    more changes to how we pass the framebuffer information on to syscons.
    Or alternatively we figure out how to tell amdgpu(4) to always use VRAM for
    the framebuffer.

Summary of changes:
 sys/dev/misc/syscons/syscons.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/f76e8b935cd9b27328877f9637a1d45dd9cdd045


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