perf tools: handle endianness of feature bitmap

			bitmap_zero(header->adds_features, HEADER_FEAT_BITS);

		else

			return -1;

	} else if (ph->needs_swap) {

		unsigned int i;

		/*

		 * feature bitmap is declared as an array of unsigned longs --

		 * not good since its size can differ between the host that

		 * generated the data file and the host analyzing the file.

		 *

		 * We need to handle endianness, but we don't know the size of

		 * the unsigned long where the file was generated. Take a best

		 * guess at determining it: try 64-bit swap first (ie., file

		 * created on a 64-bit host), and check if the hostname feature

		 * bit is set (this feature bit is forced on as of fbe96f2).

		 * If the bit is not, undo the 64-bit swap and try a 32-bit

		 * swap. If the hostname bit is still not set (e.g., older data

		 * file), punt and fallback to the original behavior --

		 * clearing all feature bits and setting buildid.

		 */

		for (i = 0; i < BITS_TO_LONGS(HEADER_FEAT_BITS); ++i)

			header->adds_features[i] = bswap_64(header->adds_features[i]);

		if (!test_bit(HEADER_HOSTNAME, header->adds_features)) {

			for (i = 0; i < BITS_TO_LONGS(HEADER_FEAT_BITS); ++i) {

				header->adds_features[i] = bswap_64(header->adds_features[i]);

				header->adds_features[i] = bswap_32(header->adds_features[i]);

			}

		}

		if (!test_bit(HEADER_HOSTNAME, header->adds_features)) {

			bitmap_zero(header->adds_features, HEADER_FEAT_BITS);

			set_bit(HEADER_BUILD_ID, header->adds_features);

		}

	}

	memcpy(&ph->adds_features, &header->adds_features,

	       sizeof(ph->adds_features));

	/*

	 * FIXME: hack that assumes that if we need swap the perf.data file

	 * may be coming from an arch with a different word-size, ergo different

	 * DEFINE_BITMAP format, investigate more later, but for now its mostly

	 * safe to assume that we have a build-id section. Trace files probably

	 * have several other issues in this realm anyway...

	 */

	if (ph->needs_swap) {

		memset(&ph->adds_features, 0, sizeof(ph->adds_features));

		perf_header__set_feat(ph, HEADER_BUILD_ID);

	}

	ph->event_offset = header->event_types.offset;

	ph->event_size   = header->event_types.size;