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SubjectRe: [PATCH 3/4] fbdev: Add FBINFO_HIDE_SMEM_START flag

On 08/22/2018 10:54 AM, Daniel Vetter wrote:
> DRM drivers really, really, really don't want random userspace to
> share buffer behind it's back, bypassing the dma-buf buffer sharing
> machanism. For that reason we've ruthlessly rejected any IOCTL
> exposing the physical address of any graphics buffer.
> Unfortunately fbdev comes with that built-in. We could just set
> smem_start to 0, but that means we'd have to hand-roll our own fb_mmap
> implementation. For good reasons many drivers do that, but
> smem_start/length is still super convenient.
> Hence instead just stop the leak in the ioctl, to keep fb mmap working
> as-is. A second patch will set this flag for all drm drivers.
> Cc: Bartlomiej Zolnierkiewicz <>
> Cc: Kees Cook <>
> Cc: Daniel Vetter <>
> Cc:
> Signed-off-by: Daniel Vetter <>

Acked-by: Bartlomiej Zolnierkiewicz <>

Best regards,
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

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