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Diffstat (limited to 'static/v10/man5/a.out.5')
| -rw-r--r-- | static/v10/man5/a.out.5 | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/static/v10/man5/a.out.5 b/static/v10/man5/a.out.5 new file mode 100644 index 00000000..15cc5e8e --- /dev/null +++ b/static/v10/man5/a.out.5 @@ -0,0 +1,150 @@ +.pa 1 +.he 'A.OUT (V)'3/15/72'A.OUT (V)' +.ti 0 +.nf +NAME a.out -- assembler and link editor output +.fi +.sp +.ti 0 +DESCRIPTION +.br +.in 8 +a.out_____ +is the output file of the assembler as__ and the link editor ld__. +In both cases, a.out_____ may be executed provided there +were no errors and no unresolved external references. +.sp +This file has four sections: +a header, the program and data text, a symbol table, and relocation bits +(in that order). +The last two may be empty +if the program was loaded +with the "-s" option +of ld__ or if the symbols and relocation have been +removed by strip_____. + +The header always contains 8 words: + +.in +6 +.ti -3 +1 A magic number (407(8)) +.ti -3 +2 The size of the program text segment +.ti -3 +3 The size of the initialized data segment +.ti -3 +4 The size of the uninitialized (bss) segment +.ti -3 +5 The size of the symbol table +.ti -3 +6 The entry location (always 0 at present) +.ti -3 +7 The stack size required (0 at present) +.ti -3 +8 A flag indicating relocation bits have been suppressed + +.in -6 +The sizes of each segment are in bytes but are even. +The size of the header is not included in any of the other sizes. + +When a file produced by the assembler or loader is +loaded into core for execution, three segments are +set up: the text segment, the data segment, +and the bss (uninitialized data) segment, +in that order. +The text segment begins at the lowest +location in the core image; the header is not loaded. +The data segment begins immediately after the text +segment, and the bss segment immediately after +the data segment. +The bss segment is initialized by 0's. +In the future the text segment will be write-protected +and shared. + +The start of the text segment in the file is 20(8); +the start of the data segment is 20+S9t8 (the size of the text) +the start of the relocation information is 20+S9t8+S9d8; +the start of the symbol table is 20+2(S9t8+S9d8) if the +relocation information is present, 20+S9t8+S9d8 if not. + +The symbol table consists of 6-word entries. The first +four contain the ASCII name of the symbol, null-padded. +The next word is a flag indicating the type of symbol. +The following values are possible: + + 00 undefined symbol + 01 absolute symbol + 02 text segment symbol + 03 data segment symbol + 04 bss segment symbol + 40 undefined external (.globl) symbol + 41 absolute external symbol + 42 text segment external symbol + 43 data segment external symbol + 44 bss segment external symbol + +Values other than those given above may +occur if the user has defined some of his own instructions. + +The last word of a symbol table entry contains the value of the symbol. + +If the symbol's type is undefined external, +and the value field is non-zero, +the symbol is interpreted by the loader ld__ as +the name of a common region +whose size is indicated by the value of the +symbol. + +The value of a word in the text or data portions which is not +a reference to an undefined external symbol +is exactly that value which will appear in core +when the file is executed. +If a word in the text or data portion +involves a reference to an undefined external symbol, +as indicated by the relocation bits +for that word, +then the value of the word as stored in the file +is an offset from the associated external symbol. +When the file is processed by the +link editor and the external symbol becomes +defined, the value of the symbol will +be added into the word in the file. + +If relocation +information is present, it amounts to one word per +word of program text or initialized data. +There is no relocation information if the "suppress relocation" +flag in the header is on. + +Bits 3-1 of a relocation word indicate the segment referred +to by the text or data word associated with the relocation +word: + +.in +6 +.ti -4 +00 indicates the reference is absolute +.ti -4 +02 indicates the reference is to the text segment +.ti -4 +04 indicates the reference is to the data segment +.ti -4 +06 indicates the reference is to the bss segment +.ti -4 +10 indicates the reference is to an undefined external symbol. + +.in -6 +Bit 0 of the relocation word indicates if on__ that the +reference is relative to the pc (e.g. "clr x"); +if off___, the reference is to the actual symbol (e.g., +"clr *$x"). + +The remainder of the relocation word (bits 15-4) +contains a symbol number in the case of external +references, and is unused otherwise. +The first symbol is numbered 0, the second 1, etc. +.sp +.in 16 +.ti 0 +SEE ALSO as__, +.ul +ld, strip, nm, un(I) |