TH 2L 1
SH NAME
0l, 1l, 2l, 4l, 5l, 6l, 7l, 8l, 9l, kl, ql, vl, xl \- loaders
SH SYNOPSIS
B 2l
[
I option ...
]
[
I file ...
]
br
etc.
SH DESCRIPTION
These commands
load the named
I files
into executable files for the corresponding architectures; see
IR 2c (1)
for the correspondence between an architecture and the character
RB ( 0 ,
RB 1 ,
etc.) that specifies it.
The files should be object files or libraries (archives of object files)
for the appropriate architecture.
Also, a name like
BI -l ext
represents the library
BI lib ext .a
in
BR /$objtype/lib ,
where
I objtype
is one of
BR 68000 ,
etc. as listed in
IR 2c (1).
The libraries must have tables of contents
(see
IR ar (1)).
PP
In practice,
B -l
options are rarely necessary as the header files for
the libraries cause their archives to be included automatically in the load
(see
IR 2c (1)).
For example, any program that includes header file
B libc.h
causes the loader
to search the C library
BR /$objtype/lib/libc.a .
Also, the loader creates an undefined symbol
B _main
(or
B _mainp
if profiling is enabled) to force loading of the
startup linkage from the C library.
PP
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
I A
needs
I B
which needs
I A
again, it may be necessary to mention
I A
explicitly so it will be read a second time.
PP
The loader options are:
TP 1i
B -l
(As a bare option.)
Suppress the default loading of the startup linkage and libraries
specified by header files.
TP
BI -o " out"
Place output in file
IR out .
Default is
IB O .out\f1,
where
I O
is the first letter of the loader name.
TP
B -p
Insert profiling code into the executable output; no special action is needed
during compilation or assembly.
TP
B -s
Strip the symbol tables from the output file.
TP
B -a
Print the object code in assembly language, with addresses.
TP
B -v
Print debugging output that annotates the activities of the load.
TP
BI -c function
RI ( Xl
only) Place the
I function
in the internal RAM of the DSP3210.
TP
BI -M
RI ( Kl
only) Generate instructions rather than calls to emulation routines
for multiply and divide.
TP
BI -m size
RI ( Xl
only) Use
I size
(default 0, maximum 8192)
bytes of internal RAM of the DSP3210 for functions and small data items.
TP
BI -E symbol
The entry point for the binary is
I symbol
(default
BR _main ;
B _mainp
under
BR -p ).
TP
BI -H n
Executable header is type
IR 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
I vl
creates a MIPS executable for an SGI Unix system.
TP
BI -T t
The text segment starts at address
IR t .
TP
BI -D d
The data segment starts at address
IR d .
TP
BI -R r
The text segment is rounded to a multiple of
I r
(if
I r
is nonzero).
PP
The numbers in the above options can begin with
L 0x
or
L 0
to change the default base from decimal to hexadecimal or octal.
The defaults for the values depend on the compiler and the
header type.
PP
The loaded image has several symbols inserted by the loader:
B etext
is the address of the end of the text segment;
B bdata
is the address of the beginning of the data segment;
B edata
is the address of the end of the data segment;
and
B end
is the address of the end of the bss segment, and of the program.
SH FILES
TF /$objtype/lib
TP
B /$objtype/lib
for
BI -l lib
arguments.
SH SOURCE
B /sys/src/cmd/2l
etc.
SH "SEE ALSO"
IR 2c (1),
IR 2a (1),
IR ar (1),
IR nm (1),
IR db (1),
IR prof (1)
PP
Rob Pike,
``How to Use the Plan 9 C Compiler''