To: simos-release@Crissy.Stanford.EDU
Subject: Announcing SimOS Release 2.0!
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The SimOS team at Stanford University is pleased to announce the
second release of our complete machine simulation environment. If you
are receiving this email, then you have downloaded an earlier version
of SimOS or were deemed "someone who may be interested". If you would
like to be taken off this infrequently used list, send mail to
"simos@cs.stanford.edu" and we'll take you off of it immediately.
For those of you who need a refresher, SimOS is a "complete machine
simulator" in that it models the hardware of uniprocessor and
multiprocessor computers in enough detail to boot and run commercial
operating systems as well as applications designed for these operating
systems. This includes databases, web servers, and other workloads
that traditional simulation tools have trouble supporting.
Furthermore, SimOS executes these workloads at high speeds
and provides support for easily collecting detailed hardware and
software performance information.
There have been substantial improvements and enhancements since the
first SimOS release including:
* Support for the Digital Alpha architecture running the Digital
Unix operating system.
* Support for the MIPS 64-bit architecture.
* More modular hardware simulator interfaces that simplify the process
of adding new processor, memory system, and device models.
SimOS is available free of charge for the research community and runs
on several different hardware platforms. For download information,
research papers, a discussion group, and more, visit the new SimOS web
site at:
http://simos.stanford.edu
Connectix VirtualPC simulates a complete PC system including VGA, Audio
Ethernet hardware and does sophisticated dynamic translation to achieve
reasonable speeds (it's not exactly clear how well that works, but it
seems that its achieved speed is between 25% and 80% native speed)
and claims ``up to twice as fast as the competition.''
http://www.connectix.com/html/connectix_virtualpc.html
and
http://www.byte.com/art/9711/sec4/art4.htm
SoftWindows 5.0 is Insignia's competitive product (``up to twice
as fast as the competition'')
Also, RealPC, also by Insignia, is closer to VirtualPC
in its design, it is a hardware-level emulator.
See http://www.insignia.com.
Another interesting product is Inferno.
See http://inferno.lucent.com.
It describes
the Inferno operating system, which is available both in native and application
form and is VM-based, using dynamic translation to achieve (allegedly) a
1.5-2.5 times slowdown over native code.
It is similar to TAOS in that it achieves application portability via
a virtual machine.
Date: Sun, 21 Jun 1998 10:50:58 -0400
Reply-To: History of Computing Issues
Sender: History of Computing Issues
From: Lee Wittenberg
Subject: SSEM Simulator
To: SHOTHC-L@SIVM.SI.EDU
X-UIDL: 2b629fc6064ad7c8f2c0919e41c76276
To coincide with the 50th Anniversary of the Small Scale Experimental
Machine at Manchester, I am releasing the first "official" version of
an SSEM simulator written in Java, and therefore (presumably)
platform-independent. Source and binaries are available at
ftp://samson.kean.edu/pub/leew/ssem/
Bochs, an Intel x86 emulator.
The New Mexico Statue University
Parallel Trace Archive
The Paradyn system uses runtime (during execution) code generation
(instrumentation).
Method for verifying contiquity of a binary translated block of instructions
by attaching a compare and/or branch instruction to predecessor block of
instructions
Abstract
A method for enabling a first block of instructions to verify whether the
first block of instructions follows a second block of instructions in an
order of execution. The method includes appending a compare instruction to
the first block of instructions. The compare instruction compares a first
value from the first block of instructions with a second value from the
second block of instructions, which precedes the first block of instructions
in the order of execution. The method further includes appending a branching
instruction to the first block of instructions. The branching instruction is
executed in response to the first value being unequal to the second value.
The branching instruction, when executed, branches to an alternative look-up
routine to obtain a block of instructions that follows the second block of
instructions in the order of execution.
http://patents.uspto.gov/cgi-bin/ifetch4?INDEX+PATBIB-ALL+0+24884+0+6+20371+OF+1+1+1+PN%2f5721927
What is claimed is:
1. A computer-implemented method for enabling a first block of instructions to verify whether the first block of instructions
follows a second block of instructions in an order of execution the method comprising the steps of:
a) appending a compare instruction to the first block of instructions, the compare instruction when executed compares a
first value from the first block of instructions with a second value from the second block of instructions, said second block
of instructions preceding said first block of instructions in the order of execution; and
b) appending a branching instruction to the first block of instructions, said branching instruction is executed in response to
the first value being unequal to the second value, said branching instruction, when executed, branches to an alternative
look-up routine to obtain a block of instructions that follows the second block of instructions in the order of execution.
U.S. REFERENCES: (No patents reference this one)
Patent
Inventor
Issued
Title
5167023
De Nicolas et al.
11 /1992
Translating a dynamic transfer control instruction address in a simulated CPU
processor
ABSTRACT: The system and method of this invention simulates the flow of control of an application program targeted for a
specific instruction set of a specific processor by utilizing a simulator running on a second processing system having a second
processor with a different instruction set. The simulator reduces the number of translated instructions needed to simulate the
flow of control of the first processor instructions when translating the address of the next executable instruction resulting from a
dynamic transfer of control, i.e., resulting from a return instruction. The simulator compares the address that is loaded at run time
by the return instruction with the return address previously executed by that instruction. If the last return address matches, the
location of the return is the same. If the last return does not match, a translate look-aside buffer is used to determine the address.
If the translate look-aside buffer does not find the address, then a binary tree look up mechanism is used to determine the
address of the next instruction after a return. The performance of the simulator is enhanced by utilizing the easiest approaches
first in the chance that a translated instruction will result most efficiently.
5287490
Sites
2 /1994
Identifying plausible variable length machine code of selecting address in numerical
sequence, decoding code strings, and following execution transfer paths
ABSTRACT: Information about the location of untranslated instructions in an original program is discovered during execution of a
partial translation of the program, and that information is used later during re-translation of the original program. Preferably the
information includes origin addresses of translated instructions and corresponding destination address of untranslated
instructions of execution transfers that occur during the execution of the partial translation. Preferably this feedback of
information from execution to re-translation is performed after each execution of the translated program so that virtually all of
the instructions in the original program will eventually be located and translated. To provide an indication of the fraction of the
code that has been translated, the program is scanned to find plausible code in the areas of memory that do not contain translated
code. The plausible code is identified by selecting addresses according to three different scanning modes and attempting to
decode variable-length instructions beginning at the selected addresses. The scanning modes include a first mode in which
addresses are selected in numerical sequence by a scan pointer, a second mode in which addresses are selected in
instruction-length sequence by an instruction decode pointer, and a third mode in which the selected addresses are destination
addresses of previously-decoded execution transfer instructions.
hat is claimed is:
26. A method of operating a digital computer having an addressable memory, said addressable memory containing a computer
program, said computer program including instructions and data at respective address locations of said addressable memory,
each of said instructions consisting of contents of a variable number of contiguous ones of said address locations depending upon
an operation specified by said each of said instructions, said method identifying address locations of said addressable memory
that appear to contain said instructions of said computer program, said method comprising the steps of:
a) selecting program addresses in numerical sequence, and attempting to decode an instruction in said addressable
memory at each program address until an initial instruction is decoded; and when said initial instruction is decoded, then
b) attempting to decode a string of instructions immediately following said initial instruction until an execution transfer
instruction is decoded, and when an attempt to decode an instruction fails, continuing said selecting program addresses
and said attempting to decode an instruction at each program address as set out in said step a), and when an execution
transfer instruction is decoded, then
c) attempting to decode an instruction at a destination address of the decoded execution transfer instruction, and when
the attempt to decode an instruction at the destination address of the decoded execution transfer instruction fails,
continuing said selecting program addresses and said attempting to decode an instruction at each program address as set
out in step a), and when the attempt to decode an instruction at the destination address of the decoded execution transfer
instruction succeeds, then identifying, as said address locations of said addressable memory that appear to contain said
instructions of said computer program, the address locations including said initial instruction and said string of instructions
including said execution transfer instruction,
wherein some program addresses of said computer program are known to contain instructions, and wherein said step a)
skips over the program addresses that are known to contain instructions,
wherein the decoding of an instruction is not permitted when an instruction being decoded partially overlaps program
addresses known to contain an instruction, and
wherein said step a) skips over a program address containing a value that is included in a predefined set of values,
regardless of whether an attempt to decode an instruction starting at the program address would be successful, wherein
said set of values includes values that indicate instructions having a length of one program address location, said set of
values includes opcodes of privileged instructions, and said set of values includes the value of zero, and
wherein said step a) skips over a program address that is the first address of a string of at least four printable ASCII
alphanumeric characters.
5560013
Scalzi et al.
9 /1996
Method of using a target processor to execute programs of a source architecture that
uses multiple address spaces
ABSTRACT: A method of utilizing large virtual addressing in a target computer to implement an instruction set translator (1ST)
for dynamically translating the machine language instructions of an alien source computer into a set of functionally equivalent
target computer machine language instructions, providing in the target machine, an execution environment for source machine
operating systems, application subsystems, and applications. The target system provides a unique pointer table in target virtual
address space that connects each source program instruction in the multiple source virtual address spaces to a target instruction
translation which emulates the function of that source instruction in the target system. The target system efficiently stores the
translated executable source programs by actually storing only one copy of any source program, regardless of the number of
source address spaces in which the source program exists. The target system efficiently manages dynamic changes in the
source machine storage, accommodating the nature of a preemptive, multitasking source operating system. The target system
preserves the security and data integrity for the source programs on a par with their security and data integrity obtainable when
executing in source processors (i.e. having the source architecture as their native architecture). The target computer execution
maintains source-architected logical separations between programs and data executing in different source address
spaces--without a need for the target system to be aware of the source virtual address spaces.
Having thus described our invention, what we claim as new and desire to secure by Letters patent is:
1. An emulation method for executing individual source instructions in a target processor to execute source programs
requiring source processor features not built into the target processor, comprising the steps of:
inputting instructions of a source processor program to an emulation target processor having significant excess virtual
addressing capacity compared to a virtual addressing capacity required for a source processor to natively execute the
source processor program, and supporting multiple source virtual address spaces in the operation of the source
processor,
building a virtual ITM (instruction translation map) in a target virtual address space supported by the target processor, the
virtual ITM containing an ITM entry for each source instruction addressable unit, each source instruction addressable
unit beginning on a source storage instruction boundary, structuring each ITM entry for containing a translation address
to a target translation program that executes a source instruction having a source address associated with the ITM entry,
determining a ratio R by dividing the length of each ITM entry by the length of each source instruction addressable unit,
accessing an ITM entry for an executing source instruction by:
generating a source aggregate virtual address for the source instruction by combining the source address of the
source instruction with a source address space identifier of a source virtual address space containing the
instruction,
multiplying the source aggregate virtual address by R to obtain a target virtual address component, and
inserting the target virtual address component into a predetermined component location in a target virtual address
to generate an ITM entry target virtual address for locating an ITM entry associated with the source instruction in
order to obtain a one-to-one addressing relationship between ITM entry target virtual addresses and source
instruction addresses.
5619665
Emma
4 /1997
Method and apparatus for the transparent emulation of an existing instruction-set
architecture by an arbitrary underlying instruction-set architecture
ABSTRACT: The invention provides means and methods for extending an instruction-set architecture without impacting the
software interface. This circumvents all software compatibility issues, and allows legacy software to benefit from new
architectural extensions without recompilation and reassembly. The means employed are a translation engine for translating
sequences of old architecture instructions into primary, new architecture instructions, and an extended instruction (EI) cache
memory for storing the translations. A processor requesting a sequence of instructions will look first to the EI-cache for a
translation, and if translations are unavailable, will look to a conventional cache memory for the sequence, and finally, if still
unavailable, will look to a main memory.
I claim:
1. A method for translating a series of one or more instructions of a first semantic type into one or more instructions of a
second semantic type, comprising the steps of:
providing a first memory;
providing a second memory;
translating a sequence of instructions of the first semantic type stored in the first memory into one or more primary
instructions of the second semantic type and storing the instructions of the second type in the second memory;
upon a request from the processor for the sequence of instructions of the first semantic type:
providing the corresponding instructions of the second semantic type if available in the second memory;
providing the sequence of instructions of the first semantic type if the corresponding instructions of the second
semantic type are not available in the second memory.
[Others found.]
4347565
Kareda et al.
8 /1982
Address control system for software simulation
ABSTRACT: An address control system for software simulation in a virtual machine system having a virtual storage function.
When a simulator program is simulating an instruction of a program to be simulated, an address translation of an operand address
in the program to be simulated is achieved using a translation lookaside buffer, thereby greatly reducing the overhead for the
address translation during the simulator program execution.
4638423
Ballard
1 /1987
Emulating computer
ABSTRACT: An apparatus and method is disclosed for providing an emulating computer. The present invention consists of a
computer having a storage area, processing unit, control circuits and translation circuit. The original instructions are first loaded
into the storage area. When the processor attempts to operate an instruction the control circuit loads a section of the instructions
into the translating circuit. These instructions are then translated and stored in a memory area of the translating circuit having the
address of the original instruction. The processor unit then accesses the storage area and retrieves the translated instruction.
What is claimed is:
7. A method of emulating a computer comprising the steps of:
transmitting an instruction to a processing unit;
checking a cache memory for a translated instruction;
loading an instruction block into an instruction memory if said translated instruction is not in said cache memory;
translating an instruction of said instruction block providing a translated instruction;
storing said translated instruction in said cache memory; and
transmitting said translated instruction from said cache memory to said processing unit.
http://www.nwlink.com/~tigger/altair.html.
Anything you know about that I haven't included
and any bugs you find that I haven't fixed.
From instruction-set simulation and tracing