On Thu, 2012-10-11 at 12:32 +0100, James Hogan wrote: > On 11/10/12 11:24, James Bottomley wrote: > > On Thu, 2012-10-11 at 10:15 +0100, James Hogan wrote: > >> The struct scsi_varlen_cdb_hdr is expected to be exactly 10 bytes when > >> used in struct osd_cdb_head, but it isn't marked as packed. Some > >> architectures will round the struct size up which triggers BUILD_BUG_ON > >> compile errors in osd_initiator.c when the outer structs are unexpected > >> sizes. This is fixed by marking struct scsi_varlen_cdb_hdr as __packed. > > > > What actual problem have you encountered? The structure is {u8[8], u16} > > which is naturally packed on every architecture I know about. I've even > > built osd_initiator without problem on parisc, which has some of the > > most rigid alignment rules I've seen. > > Hi James, > > The alignment is fine (the offset of the u16 is 8 bytes), but > unfortunately with the metag port of gcc, sizeof(struct > scsi_varlen_cdb_hdr) is rounded up to a 4 byte boundary (even though the > largest data member alignment is only 2 bytes), which is 12 bytes > instead of 10. That sounds to be a bug in your compiler ... it shouldn't be rounding up structure sizes if the structure can fit in 10 bytes. This isn't happening in any other architecture that I know of (otherwise we'd have had a reported build break). James -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html