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sim/ppc/README.psim
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@ -18,17 +18,16 @@
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
This directory contains the source code to the program PSIM that
implements a model of a PowerPC platform. PSIM can either be built
standalone or as part of the debugger GDB.
This directory contains the source code to the program PSIM.
What is PSIM?
PSIM is an ANSI C program that can be configured to model
various PowerPC platforms.
PSIM is an ANSI C program that implements an instruction
level model of the PowerPC architecture.
The platform that is modeled can vary from:
It can be configured to model various PowerPC platforms
and include:
o A user program environment (UEA) complete
with emulated system calls
@ -39,70 +38,9 @@ What is PSIM?
interacting with each other and various
modeled hardware devices.
For each of these models PSIM is able perform a detailed
analysis of the machines performance.
Is the source code available?
Yes.
The source code to PSIM is available under the terms of
the GNU Public Licence. This allows you to distribute
the source code for free but with certain conditions.
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?
@ -201,37 +139,304 @@ What features does PSIM have?
of new hardware devices so that they can be
included in a custom hardware model.
Emulation
OS-Emulation
PSIM's UEA model includes emulation for UNIX system
calls.
PSIM's OEA model includes emulation of either:
o OpenBoot client interface
o MOTO's BUG interface.
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.
Is PSIM CHRP Compliant?
What performance analysis measurements can PSIM perform?
Below is the output from a recent analysis run
(contributed by Michael Meissner):
For the following program:
long
simple_rand ()
{
static unsigned long seed = 47114711;
unsigned long this = seed * 1103515245 + 12345;
seed = this;
return this >> 8;
}
unsigned long int
random_bitstring ()
{
unsigned long int x;
int ran, n_bits;
int tot_bits = 0;
x = 0;
for (;;)
{
ran = simple_rand ();
n_bits = (ran >> 1) % 16;
tot_bits += n_bits;
if (n_bits == 0)
return x;
else
{
x <<= n_bits;
if (ran & 1)
x |= (1 << n_bits) - 1;
if (tot_bits > 8 * sizeof (long) + 6)
return x;
}
}
}
#define ABS(x) ((x) >= 0 ? (x) : -(x))
main ()
{
int i;
for (i = 0; i < 50000; i++)
{
unsigned long x, y;
x = random_bitstring ();
y = random_bitstring ();
if (sizeof (int) == sizeof (long))
goto save_time;
{ unsigned long xx = x, yy = y, r1, r2;
if (yy == 0) continue;
r1 = xx / yy;
r2 = xx % yy;
if (r2 >= yy || r1 * yy + r2 != xx)
abort ();
}
{ signed long xx = x, yy = y, r1, r2;
if ((unsigned long) xx << 1 == 0 && yy == -1)
continue;
r1 = xx / yy;
r2 = xx % yy;
if (ABS (r2) >= (unsigned long) ABS (yy) || (signed long) (r1 * yy + r2) != xx)
abort ();
}
save_time:
{ unsigned int xx = x, yy = y, r1, r2;
if (yy == 0) continue;
r1 = xx / yy;
r2 = xx % yy;
if (r2 >= yy || r1 * yy + r2 != xx)
abort ();
}
{ signed int xx = x, yy = y, r1, r2;
if ((unsigned int) xx << 1 == 0 && yy == -1)
continue;
r1 = xx / yy;
r2 = xx % yy;
if (ABS (r2) >= (unsigned int) ABS (yy) || (signed int) (r1 * yy + r2) != xx)
abort ();
}
{ unsigned short xx = x, yy = y, r1, r2;
if (yy == 0) continue;
r1 = xx / yy;
r2 = xx % yy;
if (r2 >= yy || r1 * yy + r2 != xx)
abort ();
}
{ signed short xx = x, yy = y, r1, r2;
r1 = xx / yy;
r2 = xx % yy;
if (ABS (r2) >= (unsigned short) ABS (yy) || (signed short) (r1 * yy + r2) != xx)
abort ();
}
{ unsigned char xx = x, yy = y, r1, r2;
if (yy == 0) continue;
r1 = xx / yy;
r2 = xx % yy;
if (r2 >= yy || r1 * yy + r2 != xx)
abort ();
}
{ signed char xx = x, yy = y, r1, r2;
r1 = xx / yy;
r2 = xx % yy;
if (ABS (r2) >= (unsigned char) ABS (yy) || (signed char) (r1 * yy + r2) != xx)
abort ();
}
}
exit (0);
}
Here is the current output generated with the -I switch on a 90 Mhz
pentium (the compiler used is the devlopment version of GCC with a new
scheduler replacing the old one):
CPU #1 executed 41,994 AND instructions.
CPU #1 executed 519,785 AND Immediate instructions.
CPU #1 executed 680,058 Add instructions.
CPU #1 executed 41,994 Add Extended instructions.
CPU #1 executed 921,916 Add Immediate instructions.
CPU #1 executed 221,199 Add Immediate Carrying instructions.
CPU #1 executed 943,823 Add Immediate Shifted instructions.
CPU #1 executed 471,909 Add to Zero Extended instructions.
CPU #1 executed 571,915 Branch instructions.
CPU #1 executed 1,992,403 Branch Conditional instructions.
CPU #1 executed 571,910 Branch Conditional to Link Register instructions.
CPU #1 executed 320,431 Compare instructions.
CPU #1 executed 471,911 Compare Immediate instructions.
CPU #1 executed 145,867 Compare Logical instructions.
CPU #1 executed 442,414 Compare Logical Immediate instructions.
CPU #1 executed 1 Condition Register XOR instruction.
CPU #1 executed 103,873 Divide Word instructions.
CPU #1 executed 104,275 Divide Word Unsigned instructions.
CPU #1 executed 132,510 Extend Sign Byte instructions.
CPU #1 executed 178,895 Extend Sign Half Word instructions.
CPU #1 executed 871,920 Load Word and Zero instructions.
CPU #1 executed 41,994 Move From Condition Register instructions.
CPU #1 executed 100,005 Move from Special Purpose Register instructions.
CPU #1 executed 100,002 Move to Special Purpose Register instructions.
CPU #1 executed 804,619 Multiply Low Word instructions.
CPU #1 executed 421,201 OR instructions.
CPU #1 executed 471,910 OR Immediate instructions.
CPU #1 executed 1,292,020 Rotate Left Word Immediate then AND with Mask instructions.
CPU #1 executed 663,613 Shift Left Word instructions.
CPU #1 executed 1,151,564 Shift Right Algebraic Word Immediate instructions.
CPU #1 executed 871,922 Store Word instructions.
CPU #1 executed 100,004 Store Word with Update instructions.
CPU #1 executed 887,804 Subtract From instructions.
CPU #1 executed 83,988 Subtract From Immediate Carrying instructions.
CPU #1 executed 1 System Call instruction.
CPU #1 executed 207,746 XOR instructions.
CPU #1 executed 23,740,856 cycles.
CPU #1 executed 10,242,780 stalls waiting for data.
CPU #1 executed 1 stall waiting for a function unit.
CPU #1 executed 1 stall waiting for serialization.
CPU #1 executed 1,757,900 times a writeback slot was unavilable.
CPU #1 executed 1,088,135 branches.
CPU #1 executed 2,048,093 conditional branches fell through.
CPU #1 executed 1,088,135 successful branch predictions.
CPU #1 executed 904,268 unsuccessful branch predictions.
CPU #1 executed 742,557 branch if the condition is FALSE conditional branches.
CPU #1 executed 1,249,846 branch if the condition is TRUE conditional branches.
CPU #1 executed 571,910 branch always conditional branches.
CPU #1 executed 9,493,653 1st single cycle integer functional unit instructions.
CPU #1 executed 1,220,900 2nd single cycle integer functional unit instructions.
CPU #1 executed 1,254,768 multiple cycle integer functional unit instructions.
CPU #1 executed 1,843,846 load/store functional unit instructions.
CPU #1 executed 3,136,229 branch functional unit instructions.
CPU #1 executed 16,949,396 instructions that were accounted for in timing info.
CPU #1 executed 871,920 data reads.
CPU #1 executed 971,926 data writes.
CPU #1 executed 221 icache misses.
CPU #1 executed 16,949,396 instructions in total.
Simulator speed was 250,731 instructions/second
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
interface eventually becomes 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.
Is PSIM PowerPC Platform (PPCP) (nee CHRP) Compliant?
No.
However, PSIM does include all the hooks that are needed to
construct a model of a CHRP compliant platform.
Among other things it does not have an Apple ROM socket.
That is:
o OpenBoot client software
Can PSIM be configured so that it models a CHRP machine?
o OpenPIC interrupt controller
Yes.
o Hooks to implement a RTAS interface
PSIM has been designed with the CHRP spec in mind. To model
a CHRP desktop a user would need to add the following:
o the ability to add a model of each of the
hardware devices required by a CHRP compliant
desktop.
o An apple rom socket :-)
o Model of each of the desktop IO devices
(some may already be implemented).
o An OpenPIC (Open Programmable Interrupt
Controller) device. (it may by now be
implemented).
o RTAS (Run Time Abstraction Services).
o A fully populated device tree.
Is the source code available?
Yes.
The source code to PSIM is available under the terms of
the GNU Public Licence. This allows you to distribute
the source code for free but with certain conditions.
How do I build PSIM?
@ -240,7 +445,7 @@ How do I build PSIM?
gdb-4.15.tar.gz From your favorite GNU ftp site.
I've also tested psim-951016 with
I've also tested psim with
gdb-4.15.1. If you would prefer
a graphical development environment
then PSIM can also be built with
@ -252,20 +457,26 @@ How do I build PSIM?
This file.
ftp://ftp.ci.com.au/pub/clayton/gdb-4.15+psim-951016.diff.gz
ftp://ftp.ci.com.au/pub/clayton/gdb-4.15+psim.diff.gz
This contains a few minor patches to
gdb-4.15 so that will include psim
when it is built.
Firstly this file contains a few
minor changes to gdb-4.15 so that it
will build PSIM as part of GDB.
ftp://ftp.ci.com.au/pub/clayton/psim-test-951016.tar.gz
ftp://ftp.ci.com.au/pub/clayton/gdb-4.15+note.diff.gz
(Optional) A scattering of pre-compiled
programs that run under the simulator.
Add suport for note sections (used
by OpenBoot PowerPC programs).
ftp://ftp.ci.com.au/pub/clayton/gdb-4.15+psim-951016.tar.gz
ftp://ftp.ci.com.au/pub/clayton/gdb-4.15+attach.diff.gz
Allow the gdb attach command to
work with simulators.
ftp://ftp.ci.com.au/pub/clayton/psim-960119.tar.gz
This contains the psim files proper.
@ -280,36 +491,17 @@ How do I build PSIM?
installing gnu's patch.
In addition, I'm slowly building up a set of useful patches
to gdb-4.15 that are useful. You will want to also apply
these patches:
ftp://ftp.ci.com.au/pub/clayton/gdb-4.15+attach.diff.gz
Patch to gdb that allows the `attach'
command to be used when connecting to a
simulator.
See that file for more information.
ftp://ftp.ci.com.au/pub/clayton/gdb-4.15+note.diff.gz
Patch to gdb's bfd that adds basic support
for a .note section. OpenBoot makes
use of a .note section when loading a
boot image.
Procedure:
0. A starting point
$ ls -1
gdb-4.15+psim-951016.diff.gz
gdb-4.15+psim-951016.tar.gz
gdb-4.15+attach.diff.gz
gdb-4.15+note.diff.gz
gdb-4.15+psim.diff.gz
gdb-4.15+psim.diff.gz
gdb-4.15.tar.gz
psim-test-951016.tar.gz
psim-960119.tar.gz
1. Unpack gdb
@ -322,11 +514,11 @@ How do I build PSIM?
$ 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.diff.gz | more
$ gunzip < ../gdb-4.15+psim.diff.gz | patch -p1
$ gunzip < ../gdb-4.15+psim-951016.tar.gz | tar tvf -
$ gunzip < ../gdb-4.15+psim-951016.tar.gz | tar xvf -
$ gunzip < ../gdb-4.15+psim-960119.tar.gz | tar tvf -
$ gunzip < ../gdb-4.15+psim-960119.tar.gz | tar xvf -
You may also want to consider applying the `attach' and
`note' patches that are available vis:
@ -349,6 +541,12 @@ How do I build PSIM?
eabisim is needed as by default (because PSIM needs GCC) the
simulator is not built.
[If building with a more recent gdb snapshot then the
command:
$CC=gcc ./configure --enable-sim-powerpc
is used.]
4. Build
@ -378,23 +576,7 @@ Is there a more recent version of PSIM and if so, how would I build it?
(that include new features) are made available. Several of
the more recent snapshots are:
ftp://ftp.ci.com.au/pub/clayton/psim-951219.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.
<to-be-advised>
To build/install one of these snapshots, you replace the
current gdb/sim/ppc directory with the one in the update,
@ -430,7 +612,7 @@ Are there any example programs that can be run on PSIM?
that fixes do not introduce new bugs. This test suite
like psim is updated:
ftp://ftp.ci.com.au/pub/clayton/psim-test-951218.tar.gz
ftp://ftp.ci.com.au/pub/clayton/psim-test-960118.tar.gz
Prebuilt test programs for PSIM.
Includes examples of UEA, VEA and
@ -438,11 +620,6 @@ Are there any example programs that can be run on PSIM?
Requires gcc-2.7.2 and binutils-2.6
to rebuild.
ftp://ftp.ci.com.au/pub/clayton/psim-test-951016.tar.gz
(Optional) A scattering of pre-compiled
programs that run under the simulator.
How do I use the simulator?
@ -515,9 +692,9 @@ Does PSIM have any limitations or problems?
Who helped?
Thanks go to the following who each helped in some way.
Thanks go to the following who each helped in their own
way:
Allen Briggs, Bett Koch, David Edelsohn, Gordon Irlam,
Michael Meissner, Bob Mercier, Richard Perini,
Michael Meissner, Bob Mercier, Richard Perini, Dale Rahn
Richard Stallman, Mitchele Walker