mainline kernel hardware acceleration

Code:
CC      libavcodec/v4l2_m2m.o

In file included from /usr/include/string.h:494,

                 from ./libavutil/common.h:40,

                 from ./libavutil/avutil.h:296,

                 from ./libavutil/samplefmt.h:24,

                 from ./libavcodec/avcodec.h:31,

                 from libavcodec/v4l2_m2m.c:30:

In function ‘strncpy’,

    inlined from ‘ff_v4l2_m2m_codec_init’ at libavcodec/v4l2_m2m.c:362:9:

/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin___strncpy_chk’ specified bound depends on the length of the source argument [-Wstringop-overflow=]

  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));

      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

libavcodec/v4l2_m2m.c: In function ‘ff_v4l2_m2m_codec_init’:

libavcodec/v4l2_m2m.c:362:35: note: length computed here

  362 |         strncpy(s->devname, node, strlen(node) + 1);

      |                                   ^~~~~~~~~~~~

CC      libavcodec/v4l2_m2m_dec.o

CC      libavcodec/v4l2_m2m_enc.o

CC      libavcodec/v4l2_request.o

libavcodec/v4l2_request.c: In function ‘v4l2_request_queue_decode’:

libavcodec/v4l2_request.c:216:90: error: ‘V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF’ undeclared (first use in this function)

  216 |     ret = v4l2_request_queue_buffer(ctx, req->request_fd, &req->output, last_slice ? 0 : V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF);

      |                                                                                          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

libavcodec/v4l2_request.c:216:90: note: each undeclared identifier is reported only once for each function it appears in

libavcodec/v4l2_request.c: In function ‘ff_v4l2_request_decode_slice’:

libavcodec/v4l2_request.c:300:37: error: ‘V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF’ undeclared (first use in this function)

  300 |     if ((req->output.capabilities & V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF) != V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF)

      |                                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

make: *** [ffbuild/common.mak:59: libavcodec/v4l2_request.o] Error 1

==> ERROR: A failure occurred in build().

    Aborting...