PSIM - model of a PowerPC platform
Copyright (C) 1994-1995, Andrew Cagney <cagney@highland.com.au>.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
This directory contains the program PSIM that implements a model of a
PowerPC platform. PSIM can either be built standalone or as part of
the debugger GDB.
What is PSIM?
PSIM is an ANSI C program that models a PowerPC platform.
The platform it implements can vary from:
o A user program environment (UEA) complete
with emulated system calls
to
o A hardware platform with several processors
interacting with each other and modeled hardware.
What motivated PSIM?
As an idea, psim was first discussed seriously during mid
1994. At that time its main objectives were:
o good performance
Many simulators loose out by only providing
a binary interface to the internals. This
inteface eventually becomming a bottle neck
in the simulators performance.
It was intended that PSIM would avoid this
problem by giving the user access to the
full source code.
Further, by exploiting the power of modern
compilers it was hoped that PSIM would achieve
good performance with out having to compromize
its internal design.
o practical portability
Rather than try to be portable to every
C compiler on every platform, it was decided
that PSIM would restrict its self to suporting
ANSI compilers that included the extension
of a long long type.
GCC is one such compiler, consequenly PSIM
should be portable to any machine running GCC.
o flexability in its design
PSIM should allow the user to select the
features required and customize the build
accordingly. By having the source code,
the compler is able to eliminate any un
used features of the simulator.
After all, let the compiler do the work.
o SMP
A model that allowed the simulation of
SMP platforms with out the large overhead
often encountered with such models.
PSIM achieves each of these objectives.
Who would be interested in PSIM?
o the curious
Using psim, gdb, gcc and binutils the curious
user can contruct an environment that allows
them to play with PowerPC user programs with out
the need for real hardware.
o the analyst
PSIM includes many (contributed) monitoring
features which (unlike many other simulators)
do not come with a great penalty in performance.
Thus the performance analyst is able to use
this simulator to model the inpact of changes
to the system they are analysing. Be that
system a compiler or real hardware platform.
If PSIM doesn't monitor a components of interest,
the source code is freely available, and hence
there is no hinderance to changing things
to meet a specific analysts needs.
o the serious SW developer
PSIM models all three levels of the PowerPC
Architecture: UEA, VEA and OEA. Further,
the internal design is such that PSIM can
be extended to suport additional
development requirements. Such requirements
might include (for the UEA) a new Operating
System emulation through to (for the OEA)
a model of a different hardware platform.
What features does PSIM have?
Monitoring and modeling
PSIM includes (thanks to Michael Meissner)
a detailed model of the various PowerPC
implementations schedulers.
SMP
The PowerPC ISA defines SMP synchronizing instructions
this simulator models a limited subset of their
behavor. Consequently, if you limit code to the
use the modeled behavour, PSIM can be used to
model SMP PowerPC platforms.
People intending to use this system should study
the code implementing the lwarx etc instructions.
ENDIAN SUPORT
PSIM implements all of Big-endian, little-endian
and PowerPC little endian (XOR endian).
ISA models
PSIM includes a model of UEA, VEA and OEA. This
inclues the time base registers (VEA) and HTAB
and BATS (OEA).
In addition, a preliminary model of the 64 bit
PowerPC architecture is included.
Hardware
PSIM's internals are based around the concept
of a Device Tree. This tree intentionaly
resembles that of the Device Tree found in
OpenBoot firmware. Psim is flexable enough
to allow the user to fully configure the
actual hardware model from a device tree
specification taken from a file.
PSIM also contains several built in device
trees.
Emulation
PSIM is able (UEA) to emulate UNIX calls
based on NetBSD abi through to (preliminary)
the ROM rom calls found in common firmware
(OpenBoot and BUGAPI).
floating point
Preliminary suport for floating point is included.
Real kernels don't need floating point.
Can PSIM model a CHRP a.k.a. PowerPC Platform machine?
No. but that is now one of its main objectives. (Did you notice
it was written PowerPC Platform instead of PowerPC platform?).
How do I build PSIM?
To build PSIM you will need the following:
gdb-4.15.tar.gz From your favorite GNU ftp site.
I've also tested psim-951016 with
gdb-4.15.1.
ftp://ftp.ci.com.au/pub/clayton/README.pim
This file.
ftp://ftp.ci.com.au/pub/clayton/gdb-4.15+psim-951016.diff.gz
This contains a few minor patches to
gdb-4.15 so that will include psim
when it is built.
ftp://ftp.ci.com.au/pub/clayton/gdb-4.15+psim-951016.tar.gz
This contains the psim files propper.
ftp://ftp.ci.com.au/pub/clayton/psim-test-951016.tar.gz
(Optional) A scattering of pre-compiled
programs that run under the simulator.
gcc Again available from your favorite
GNU ftp site.
patch Sun's patch behaves a little wierd
and doesn't appear to like creating
empty files.
Since PSIM is still being developed, from time to time, to meet
a specific analysts needsfurther psim snap shots are occasionally
made available. These snapshots may or may not work with GDB-4.15.
Several of the more recent snapshots are:
ftp://ftp.ci.com.au/pub/clayton/psim-951218.tar.gz
Hopefully merges in Michael stuff
with mine, adds multiple emulations
(OpenBoot and NetBSD), revamps
inline stuff, rearanges devices so
that phandls and ihandles can be
implemented.
ftp://ftp.ci.com.au/pub/clayton/psim-951203.tar.gz
A good snapshot
This includes extensions from Michael
Meissner that add monitoring of the
PowerPC's register and bus architectures.
ftp://ftp.ci.com.au/pub/clayton/psim-test-951218.tar.gz
Prebuilt test programs for PSIM.
Includes examples of UEA, VEA and
OEA code.
Requires gcc-2.7.2 and binutils-2.6
to rebuild.
Procedure:
0. A starting point
$ ls -1
gdb-4.15+psim-951016.diff.gz
gdb-4.15+psim-951016.tar.gz
gdb-4.15.tar.gz
psim-test-951016.tar.gz
1. Unpack gdb
$ gunzip < gdb-4.15.tar.gz | tar xf -
2. Change to the gdb directory, apply the psim patches and unpack
the psim files.
$ cd gdb-4.15
$ gunzip < ../gdb-4.15+psim-951016.diff.gz | more
$ gunzip < ../gdb-4.15+psim-951016.diff.gz | patch -p1
$ gunzip < ../gdb-4.15+psim-951016.tar.gz | tar tvf -
$ gunzip < ../gdb-4.15+psim-951016.tar.gz | tar xvf -
3. Configure gdb
$ more gdb/README
then something like (I assume SH):
$ CC=gcc ./configure --target=powerpc-unknown-eabisim
eabisim is needed as by default (because PSIM needs GCC) the
simulator is not built.
4. Build
$ make CC=gcc
alternativly, if you are short on disk space or just want the
simulator built:
$ ( cd libiberty && make CC=gcc )
$ ( cd bfd && make CC=gcc )
$ ( cd sim/ppc && make CC=gcc )
5. Install
$ make CC=gcc install
or just
$ cp gdb/gdb ~/bin/powerpc-unknown-eabisim-gdb
$ cp sim/ppc/run ~/bin/powerpc-unknown-eabisim-run
How do I use the simulator?
(I assume that you've unpacked the psim-test archive).
1. As a standalone program
Print out the users environment:
$ powerpc-unknown-eabisim-run envp
Print out the arguments:
$ powerpc-unknown-eabisim-run argv a b c
Check that sbrk works:
$ powerpc-unknown-eabisim-run break
2. Example of running GDB:
The main thing to note is that before you can run the simulator
you must enable it. The example below illustrates this:
$ powerpc-unknown-eabisim-gdb envp
(gdb) target sim
(gdb) load
(gdb) break main
(gdb) run
.
.
.
Where do I send bugs or report problems?
There is a mailing list (subscribe through majordomo@ci.com.au) (that
is almost never used) at:
powerpc-psim@ci.com.au
If I get the ftp archive updated I post a note to that mailing list.
In addition your welcome to send bugs or problems either to me or to
that e-mail list.
Are there any known problems?
See the ChangeLog file looking for lines taged with the word FIXME.
COREFILE.C: The implementation of corefile.c (defined by
corefile.h) isn't the best. It is intended to be functionaly
correct rather than fast. One option being considered
is to add a data cache to reduce the overhead of the most
common case of data read/writes.
HTAB (page) code for OEA model untested. Some of the vm code
instructions unimplemented.
Lacks PowerOpen (a.k.a. XCOFF a.k.a. AIX) and NT startups. The
PowerOpen worked until I added the ELF one.
Missing VEA system calls.
Missing or commented out instructions.
64bit target untested.
64bit host broken. For instance use of scanf "%x", &long long.
Event code for pending events from within signal handlers not
finished/tested.
Better and more devices.
PORTABILITY (Notes taken from Michael Meissner): Heavy use of the ##
operator - fix using the clasic X/**/Y hack; Use of the signed
keyword. In particular, signed char has no analogue in classic C
(though most implementations of classic C use signed chars); Use of
long long which restricts the target compiler to be GCC.
Who helped?
Thanks go to the following who each helped in some way.
Allen Briggs, Bett Koch, David Edelsohn, Gordon Irlam,
Michael Meissner, Bob Mercier, Richard Perini,
Richard Stallman, Mitchele Walker
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