2L(1) 2L(1)
NAME
0l, 1l, 2l, 5l, 6l, 7l, 8l, 9l, kl, ql, tl, vl - loaders
SYNOPSIS
2l [ option ... ] [ file ... ]
etc.
DESCRIPTION
These commands load the named files into executable files
for the corresponding architectures; see 2c(1) for the cor-
respondence 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 /$objtype/lib, where objtype is one of
68000, etc. as listed in 2c(1). The libraries must have
tables of contents (see ar(1)).
In practice, -l options are rarely necessary as the header
files for the libraries cause their archives to be included
automatically in the load (see 2c(1)). For example, any pro-
gram that includes header file libc.h causes the loader to
search the C library /$objtype/lib/libc.a. Also, the loader
creates an undefined symbol _main (or _mainp if profiling 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 resolve remaining symbols by searching in
topological order libraries mentioned in header files
included by files already loaded. When scanning 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 necessary 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 action is needed during compilation or assem-
bly.
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2L(1) 2L(1)
-e Insert (embedded) tracing code into the executable
output; no special action is needed during compila-
tion or assembly. The added code calls `_tracein' at
function entries and `_traceout' at function exits.
-F (ARM only) Don't generate VFP hardware floating point
instructions.
-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.
-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.
-t (5l and vl only) Move strings into the text segment.
-Hn Executable header is type n. The meaning of the types
is architecture-dependent; typically type 1 is Plan 9
boot format and type 2 is the regular Plan 9 format,
the default. These are reversed 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 nonzero).
The numbers in the above options can begin with `0x' or `0'
to change the default base from decimal to hexadecimal or
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2L(1) 2L(1)
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 pro-
gram.
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 provided by third parties.
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