Hi, Ning,
unsigned long userptr; <<<--- this is a 32bit addr.
I think it's wrong here,for LP64 data modelmachine(unix-like systems), the
actual size ofdata type 'unsigned long'is 8(64bits value)whichis equal
to pointer.
On 10/12/2018 11:04 AM, Zhang, Ning A wrote:
> Hi,
>
> I have question about V4L2_MEMORY_USERPTR on 64bit applications.
>
> struct v4l2_buffer {
> __u32 index;
> __u32 type;
> __u32 bytesused;
> __u32 flags;
> __u32 field;
> struct timeval timestamp;
> struct v4l2_timecode timecode;
> __u32 sequence;
>
> /* memory location */
> __u32 memory;
> union {
> __u32 offset;
> unsigned long userptr; <<<--- this is a 32bit addr.
> struct v4l2_plane *planes;
> __s32 fd;
> } m;
> __u32 length;
> __u32 reserved2;
> __u32 reserved;
> };
>
> when use a 64bit application, memory from malloc is 64bit address.
> memory from GPU (eg, intel i915) are also 64bit address.
>
> when use these kind of memory as V4L2_MEMORY_USERPTR, address will be
> truncated into 32bit.
>
> this would be error, but actually not. I really don't understand.
>
> BR.
> Ning.
