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auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=cohuck@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=cohuck@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/11/09 00:04:29 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Thomas Huth , David Hildenbrand , qemu-devel@nongnu.org, Halil Pasic , Christian Borntraeger , "open list:S390-ccw boot" , Paolo Bonzini , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, 5 Nov 2020 17:19:00 -0500 Daniele Buono wrote: > S390IPLState contains two IplParameterBlock, which may in turn have > either a IPLBlockPV or a IplBlockFcp, both ending with a variable > sized field (an array). > > This causes a warning with clang 11 or greater, which checks that > variable sized type are only allocated at the end of the struct: > > In file included from ../qemu-cfi-v3/target/s390x/diag.c:21: > ../qemu-cfi-v3/hw/s390x/ipl.h:161:23: error: field 'iplb' with variable sized type 'IplParameterBlock' (aka 'union IplParameterBlock') not at the end of a struct or class is a GNU extension [-Werror,-Wgnu-variable-sized-type-not-at-end] > IplParameterBlock iplb; > ^ > ../qemu-cfi-v3/hw/s390x/ipl.h:162:23: error: field 'iplb_pv' with variable sized type 'IplParameterBlock' (aka 'union IplParameterBlock') not at the end of a struct or class is a GNU extension [-Werror,-Wgnu-variable-sized-type-not-at-end] > IplParameterBlock iplb_pv; > > In this case, however, the warning is a false positive, because > IPLBlockPV and IplBlockFcp are allocated in a union wrapped at 4K, > making the union non-variable sized. > > Fix the warning by turning the two variable sized arrays into arrays > of size 0. This avoids the compiler error and should produce the > same code. > > Signed-off-by: Daniele Buono > --- > There is the possibility of removing IplBlockFcp from > IplParameterBlock, since it is not actually used. > This would also allow to entirely remove the definition of > IplBlockFcp, but we may want to keep it for completeness. We can easily do that in the future clean-up round, if we want that. > > hw/s390x/ipl.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/hw/s390x/ipl.h b/hw/s390x/ipl.h > index 9e90169695..dfc6dfd89c 100644 > --- a/hw/s390x/ipl.h > +++ b/hw/s390x/ipl.h > @@ -32,7 +32,7 @@ struct IPLBlockPV { > uint32_t num_comp; /* 0x74 */ > uint64_t pv_header_addr; /* 0x78 */ > uint64_t pv_header_len; /* 0x80 */ > - struct IPLBlockPVComp components[]; > + struct IPLBlockPVComp components[0]; > } QEMU_PACKED; > typedef struct IPLBlockPV IPLBlockPV; > > @@ -63,7 +63,7 @@ struct IplBlockFcp { > uint64_t br_lba; > uint32_t scp_data_len; > uint8_t reserved6[260]; > - uint8_t scp_data[]; > + uint8_t scp_data[0]; > } QEMU_PACKED; > typedef struct IplBlockFcp IplBlockFcp; > For now, this is a nicely small patch. Acked-by: Cornelia Huck