Full Generic System V ABI

SectionsAn object file’s section header table lets one locate all the file’s sections. The sectionheader table is an array of E l f 32 _ S h d r structures as described below. A sectionheader table index is a subscript into this array. The ELF header’s e _ s h o f fmember gives the byte offset from the beginning of the file to the section headertable; e _ s h n u m tells how many entries the section header table contains;e _ s h e n t s i z e gives the size in bytes of each entry.Some section header table indexes are reserved; an object file will not have sectionsfor these special indexes.Figure 4-7: Special Section Indexes________________________Name ValueS H N _ U N D E F ⎜ 0S H N _ L O R E S E R V E ⎜ 0 x f f 00⎜S H N _ L O P R O C ⎜ 0 x f f 00S H N _ H I P R O C ⎜ 0 x f f 1 fS H N _ A B S ⎜ 0 x f f f 1S H N _ C O M M O N ⎜ 0 x f f f 2S H N _ H I R E S E R V E ⎜ 0 x f f f f________________________⎜S H N _ U N D E FThis value marks an undefined, missing, irrelevant, or otherwisemeaningless section reference. For example, a symbol‘‘defined’’ relative to section number S H N _ U N D E F is anundefined symbol.NOTEAlthough index 0 is reserved as the undefined value, the section header tablecontains an entry for index 0. That is, if the e _ s h n u m member of the ELFheader says a file has 6 entries in the section header table, they have theindexes 0 through 5. The contents of the initial entry are specified later in thissection.S H N _ L O R E S E R V E This value specifies the lower bound of the range of reservedindexes.S H N _ L O P R O C through S H N _ H I P R O CValues in this inclusive range are reserved for processorspecificsemantics. If meanings are specified, the processorsupplement explains them.4-10 OBJECT FILES