[Qemu-devel] Block warning messages displayed while compiling

[Programmingkid]

Host info:
Operating system: Mac OS 10.12.5
Compiler: Apple LLVM version 8.1.0 (clang-802.0.42)
Command to reproduce: ./configure --target-list=ppc-softmmu,i386-softmmu && 
make -j 4

When compiling QEMU I see these warning messages:


  CC      block/vdi.o
block/qcow.c:138:19: warning: taking address of packed member 'magic' of class 
or
      structure 'QCowHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    be32_to_cpus(&header.magic);
                  ^~~~~~~~~~~~
block/qcow.c:139:19: warning: taking address of packed member 'version' of 
class or
      structure 'QCowHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    be32_to_cpus(&header.version);
                  ^~~~~~~~~~~~~~
block/qcow.c:140:19: warning: taking address of packed member 
'backing_file_offset' of
      class or structure 'QCowHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    be64_to_cpus(&header.backing_file_offset);
                  ^~~~~~~~~~~~~~~~~~~~~~~~~~
block/qcow.c:141:19: warning: taking address of packed member 
'backing_file_size' of
      class or structure 'QCowHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    be32_to_cpus(&header.backing_file_size);
                  ^~~~~~~~~~~~~~~~~~~~~~~~
block/qcow.c:142:19: warning: taking address of packed member 'mtime' of class 
or
      structure 'QCowHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    be32_to_cpus(&header.mtime);
                  ^~~~~~~~~~~~
block/qcow.c:143:19: warning: taking address of packed member 'size' of class or
      structure 'QCowHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    be64_to_cpus(&header.size);
                  ^~~~~~~~~~~
block/qcow.c:144:19: warning: taking address of packed member 'crypt_method' of 
class or
      structure 'QCowHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    be32_to_cpus(&header.crypt_method);
                  ^~~~~~~~~~~~~~~~~~~
block/qcow.c:145:19: warning: taking address of packed member 'l1_table_offset' 
of class
      or structure 'QCowHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    be64_to_cpus(&header.l1_table_offset);
                  ^~~~~~~~~~~~~~~~~~~~~~
block/vdi.c:182:19: warning: taking address of packed member 'signature' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    le32_to_cpus(&header->signature);
                  ^~~~~~~~~~~~~~~~~
block/vdi.c:183:19: warning: taking address of packed member 'version' of class 
or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    le32_to_cpus(&header->version);
                  ^~~~~~~~~~~~~~~
block/vdi.c:184:19: warning: taking address of packed member 'header_size' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    le32_to_cpus(&header->header_size);
                  ^~~~~~~~~~~~~~~~~~~
block/vdi.c:185:19: warning: taking address of packed member 'image_type' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    le32_to_cpus(&header->image_type);
                  ^~~~~~~~~~~~~~~~~~
block/vdi.c:186:19: warning: taking address of packed member 'image_flags' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    le32_to_cpus(&header->image_flags);
                  ^~~~~~~~~~~~~~~~~~~
block/vdi.c:187:19: warning: taking address of packed member 'offset_bmap' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    le32_to_cpus(&header->offset_bmap);
                  ^~~~~~~~~~~~~~~~~~~
block/vdi.c:188:19: warning: taking address of packed member 'offset_data' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    le32_to_cpus(&header->offset_data);
                  ^~~~~~~~~~~~~~~~~~~
block/vdi.c:189:19: warning: taking address of packed member 'cylinders' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    le32_to_cpus(&header->cylinders);
                  ^~~~~~~~~~~~~~~~~
block/vdi.c:190:19: warning: taking address of packed member 'heads' of class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    le32_to_cpus(&header->heads);
                  ^~~~~~~~~~~~~
block/vdi.c:191:19: warning: taking address of packed member 'sectors' of class 
or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    le32_to_cpus(&header->sectors);
                  ^~~~~~~~~~~~~~~
block/vdi.c:192:19: warning: taking address of packed member 'sector_size' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    le32_to_cpus(&header->sector_size);
                  ^~~~~~~~~~~~~~~~~~~
block/vdi.c:193:19: warning: taking address of packed member 'disk_size' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    le64_to_cpus(&header->disk_size);
                  ^~~~~~~~~~~~~~~~~
block/vdi.c:194:19: warning: taking address of packed member 'block_size' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    le32_to_cpus(&header->block_size);
                  ^~~~~~~~~~~~~~~~~~
block/vdi.c:195:19: warning: taking address of packed member 'block_extra' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    le32_to_cpus(&header->block_extra);
                  ^~~~~~~~~~~~~~~~~~~
block/vdi.c:196:19: warning: taking address of packed member 'blocks_in_image' 
of class
      or structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    le32_to_cpus(&header->blocks_in_image);
                  ^~~~~~~~~~~~~~~~~~~~~~~
block/vdi.c:197:19: warning: taking address of packed member 'blocks_allocated' 
of class
      or structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    le32_to_cpus(&header->blocks_allocated);
                  ^~~~~~~~~~~~~~~~~~~~~~~~
block/vdi.c:198:22: warning: taking address of packed member 'uuid_image' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    qemu_uuid_bswap(&header->uuid_image);
                     ^~~~~~~~~~~~~~~~~~
block/vdi.c:199:22: warning: taking address of packed member 'uuid_last_snap' 
of class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    qemu_uuid_bswap(&header->uuid_last_snap);
                     ^~~~~~~~~~~~~~~~~~~~~~
block/vdi.c:200:22: warning: taking address of packed member 'uuid_link' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    qemu_uuid_bswap(&header->uuid_link);
                     ^~~~~~~~~~~~~~~~~
block/vdi.c:201:22: warning: taking address of packed member 'uuid_parent' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    qemu_uuid_bswap(&header->uuid_parent);
                     ^~~~~~~~~~~~~~~~~~~
block/vdi.c:206:19: warning: taking address of packed member 'signature' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    cpu_to_le32s(&header->signature);
                  ^~~~~~~~~~~~~~~~~
block/vdi.c:207:19: warning: taking address of packed member 'version' of class 
or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    cpu_to_le32s(&header->version);
                  ^~~~~~~~~~~~~~~
block/vdi.c:208:19: warning: taking address of packed member 'header_size' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    cpu_to_le32s(&header->header_size);
                  ^~~~~~~~~~~~~~~~~~~
block/vdi.c:209:19: warning: taking address of packed member 'image_type' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    cpu_to_le32s(&header->image_type);
                  ^~~~~~~~~~~~~~~~~~
block/vdi.c:210:19: warning: taking address of packed member 'image_flags' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    cpu_to_le32s(&header->image_flags);
                  ^~~~~~~~~~~~~~~~~~~
block/vdi.c:211:19: warning: taking address of packed member 'offset_bmap' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    cpu_to_le32s(&header->offset_bmap);
                  ^~~~~~~~~~~~~~~~~~~
block/vdi.c:212:19: warning: taking address of packed member 'offset_data' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    cpu_to_le32s(&header->offset_data);
                  ^~~~~~~~~~~~~~~~~~~
block/vdi.c:213:19: warning: taking address of packed member 'cylinders' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    cpu_to_le32s(&header->cylinders);
                  ^~~~~~~~~~~~~~~~~
block/vdi.c:214:19: warning: taking address of packed member 'heads' of class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    cpu_to_le32s(&header->heads);
                  ^~~~~~~~~~~~~
block/vdi.c:215:19: warning: taking address of packed member 'sectors' of class 
or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    cpu_to_le32s(&header->sectors);
                  ^~~~~~~~~~~~~~~
block/vdi.c:216:19: warning: taking address of packed member 'sector_size' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    cpu_to_le32s(&header->sector_size);
                  ^~~~~~~~~~~~~~~~~~~
block/vdi.c:217:19: warning: taking address of packed member 'disk_size' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    cpu_to_le64s(&header->disk_size);
                  ^~~~~~~~~~~~~~~~~
block/vdi.c:218:19: warning: taking address of packed member 'block_size' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    cpu_to_le32s(&header->block_size);
                  ^~~~~~~~~~~~~~~~~~
block/vdi.c:219:19: warning: taking address of packed member 'block_extra' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    cpu_to_le32s(&header->block_extra);
                  ^~~~~~~~~~~~~~~~~~~
block/vdi.c:220:19: warning: taking address of packed member 'blocks_in_image' 
of class
      or structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    cpu_to_le32s(&header->blocks_in_image);
                  ^~~~~~~~~~~~~~~~~~~~~~~
block/vdi.c:221:19: warning: taking address of packed member 'blocks_allocated' 
of class
      or structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    cpu_to_le32s(&header->blocks_allocated);
                  ^~~~~~~~~~~~~~~~~~~~~~~~
block/vdi.c:222:22: warning: taking address of packed member 'uuid_image' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    qemu_uuid_bswap(&header->uuid_image);
                     ^~~~~~~~~~~~~~~~~~
block/vdi.c:223:22: warning: taking address of packed member 'uuid_last_snap' 
of class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    qemu_uuid_bswap(&header->uuid_last_snap);
                     ^~~~~~~~~~~~~~~~~~~~~~
block/vdi.c:224:22: warning: taking address of packed member 'uuid_link' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    qemu_uuid_bswap(&header->uuid_link);
                     ^~~~~~~~~~~~~~~~~
block/vdi.c:225:22: warning: taking address of packed member 'uuid_parent' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    qemu_uuid_bswap(&header->uuid_parent);
                     ^~~~~~~~~~~~~~~~~~~
block/vdi.c:440:36: warning: taking address of packed member 'uuid_link' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    } else if (!qemu_uuid_is_null(&header.uuid_link)) {
                                   ^~~~~~~~~~~~~~~~
block/vdi.c:444:36: warning: taking address of packed member 'uuid_parent' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    } else if (!qemu_uuid_is_null(&header.uuid_parent)) {
                                   ^~~~~~~~~~~~~~~~~~
block/vdi.c:798:25: warning: taking address of packed member 'uuid_image' of 
class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    qemu_uuid_generate(&header.uuid_image);
                        ^~~~~~~~~~~~~~~~~
block/vdi.c:799:25: warning: taking address of packed member 'uuid_last_snap' 
of class or
      structure 'VdiHeader' may result in an unaligned pointer value
      [-Waddress-of-packed-member]
    qemu_uuid_generate(&header.uuid_last_snap);