term% cat index.txt 2L(1) General Commands Manual 2L(1)
NAME
0l, 1l, 2l, 5l, 6l, 7l, 8l, kl, ql, vl - loaders
SYNOPSIS
2l [ option ... ] [ file ... ]
etc.
DESCRIPTION
These commands load the named files into executable files for the cor‐
responding architectures; see 2c(1) for the correspondence between an
architecture and the character (1, 2, etc.) that specifies it. The
files should be object files or libraries (archives of object files)
for the appropriate architecture. Also, a name like -lext represents
the library libext.a in /$objtype/lib, where objtype is one of 68000,
etc. as listed in 2c(1). The libraries must have tables of contents
(see ar(1)).
In practice, -l options are rarely necessary as the header files for
the libraries cause their archives to be included automatically in the
load (see 2c(1)). For example, any program that includes header file
libc.h causes the loader to search the C library /$objtype/lib/libc.a.
Also, the loader creates an undefined symbol _main (or _mainp if pro‐
filing is enabled) to force loading of the startup linkage from the C
library.
The order of search to resolve undefined symbols is to load all files
and libraries mentioned explicitly on the command line, and then to re‐
solve remaining symbols by searching in topological order libraries
mentioned in header files included by files already loaded. When scan‐
ning such libraries, the algorithm is to scan each library repeatedly
until no new undefined symbols are picked up, then to start on the next
library. Thus if library A needs B which needs A again, it may be nec‐
essary to mention A explicitly so it will be read a second time.
The loader options are:
-l (As a bare option.) Suppress the default loading of the startup
linkage and libraries specified by header files.
-o out Place output in file out. Default is O.out, where O is the
first letter of the loader name.
-p Insert profiling code into the executable output; no special ac‐
tion is needed during compilation or assembly.
-e Insert (embedded) tracing code into the executable output; no
special action is needed during compilation or assembly. The
added code calls at function entries and at function exits.
-F (ARM only) Don't generate VFP hardware floating point instruc‐
tions.
-s Strip the symbol tables from the output file.
-a Print the object code in assembly language, with addresses.
-v Print debugging output that annotates the activities of the
load.
-M (Kl only) Generate instructions rather than calls to emulation
routines for multiply and divide.
-Esymbol
The entry point for the binary is symbol (default _main; _mainp
under -p).
-x [ file ]
Produce an export table in the executable. The optional file
restricts the exported symbols to those listed in the file. See
dynld(2).
-u [ file ]
Produce an export table, import table and a dynamic load section
in the executable. The optional file restricts the imported
symbols to those listed in the file. See dynld(2).
-t (5l and vl only) Move strings into the text segment.
-Hn Executable header is type n. The meaning of the types is archi‐
tecture-dependent; typically type 1 is Plan 9 boot format and
type 2 is the regular Plan 9 format, the default. These are re‐
versed on the MIPS. The Next boot format is 3. Type 4 in vl
creates a MIPS executable for an SGI Unix system.
-Tt The text segment starts at address t.
-Dd The data segment starts at address d.
-Rr The text segment is rounded to a multiple of r (if r is non‐
zero).
The numbers in the above options can begin with or to change the de‐
fault base from decimal to hexadecimal or octal. The defaults for the
values depend on the compiler and the header type.
The loaded image has several symbols inserted by the loader: etext is
the address of the end of the text segment; bdata is the address of the
beginning of the data segment; edata is the address of the end of the
data segment; and end is the address of the end of the bss segment, and
of the program.
FILES
/$objtype/lib
for -llib arguments.
SOURCE
/sys/src/cmd/2l etc.
SEE ALSO
2c(1), 2a(1), ar(1), nm(1), db(1), prof(1)
Rob Pike, ``How to Use the Plan 9 C Compiler''
BUGS
The list of loaders given above is only partial, not all architectures
are supported on all systems, some have been retired and some are pro‐
vided by third parties.
2L(1)