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OVP Virtual Platform: BareMetalArm7Single

What is a Bare Metal Platform?

A 'Bare Metal' Platform consists of a single processor with memory available over its complete address range.



This is ideal for execution of a user application that has been compiled for the target processor core using cross-compilation.

Obtaining the BareMetalArm7Single platform and the OVP Simulator

The source and binary of the bare metal platforms are part of the OVP/Imperas downloads and live on a VLNV (Vendor Library Name Version) path.

To download from OVPworld, browse the OVP downloads page and download the OVPsim package. Click here to browse available downloads.

When installed this platform is found in your installation here: ImperasLib/source/arm.ovpworld.org/platform/BareMetalArm7Single/1.0.

Running the Bare Metal Platform

1. Run the installer to install into a local directory on your PC. We recommend you use a path without spaces, for example your home directory.

2. Enter the Demo Directory IMPERAS_HOME/Demo/BareMetalArm7Single

3. On Windows, double-click on the batch file xx.bat and on Linux run the script xx.sh to run a simple application elf file on the Bare Metal Platform.

You will see output something like:

Setting Up for Re-building the Application

To rebuild the application and create the elf file you will need 3 things:

• Cross-Compiler toolchain for thi processor
• An OVP Installation
• MSYS / MINGW environment (Windows Users Only)

Download and Installing the Cross-Compiler Toolchain

To download an appropriate tool chain, browse the OVP downloads page and download the package. Click here to browse.
If there is not one available please ask on the forum.

Once downloaded run the installer <packageName>.Windows32.exe for Windows and <packageName>.Linux32.exe for Linux to install on your PC.

Installing MSYS / MINGW Environment (Windows Users Only)

Obtaining and installing the MSYS and MINGW environment is described in Imperas_Installation_and_Getting_Started.pdf.

Rebuilding

You will need to be in the Demo/'baremetaldemodir' directory using an MSYS shell for Windows or a Linux shell.

Re-building the Application
> make application

Re-building the Bare Metal Platform
> make platform

Executing the application on the platform
You can just double click on the .bat file as done previously, or you can run from the msys command line:
> ./BareMetal.OS.exe hello.CROSS.elf

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This page provides detailed information about the OVP Virtual Platform Model of the arm.ovpworld.org BareMetalArm7Single platform.

Description

Bare Metal Platform for an ARM7 Processor. The bare metal platform instantiates a single ARM7 processor instance. The processor operates using little endian data ordering. It creates contiguous memory from 0x00000000 to 0xFFFFFFFF. The platform can be passed any application compiled to an ARM elf format. ./platform.exe application.elf

Licensing

Open Source Apache 2.0

Limitations

BareMetal platform for execution of ARM binary files compiled with Linaro 32-bit CrossCompiler toolchain.

Reference

None, BareMetal platform definition

Location

The BareMetalArm7Single virtual platform is located in an Imperas/OVP installation at the VLNV: arm.ovpworld.org / platform / BareMetalArm7Single / 1.0.

Platform Summary

Table : Components in platform

Platform Simulation Attributes

Table 1: Platform Simulation Attributes

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Command Line Control of the Platform

Built-in Arguments

Table 2: Platform Built-in Arguments

When running a platform in a Windows or Linux shell several command arguments can be specified. Typically there is a '-help' command which lists the commands available in the platforms.
For example: myplatform.exe -help

Some command line arguments require a value to be provided.
For example: myplatform.exe -program myimagefile.elf

Platform Specific Command Line Arguments

No platform specific command line arguments have been specified.

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Processor [arm.ovpworld.org/processor/arm/1.0] instance: cpu1

Processor model type: 'arm' variant 'ARM7TDMI' definition

Imperas OVP processor models support multiple variants and details of the variants implemented in this model can be found in:
- the Imperas installation located at ImperasLib/source/arm.ovpworld.org/processor/arm/1.0/doc
- the OVP website: OVP_Model_Specific_Information_arm_ARM7TDMI.pdf

Description

ARM Processor Model

Licensing

Usage of binary model under license governing simulator usage.
Note that for models of ARM CPUs the license includes the following terms:
Licensee is granted a non-exclusive, worldwide, non-transferable, revocable licence to:
If no source is being provided to the Licensee: use and copy only (no modifications rights are granted) the model for the sole purpose of designing, developing, analyzing, debugging, testing, verifying, validating and optimizing software which: (a) (i) is for ARM based systems; and (ii) does not incorporate the ARM Models or any part thereof; and (b) such ARM Models may not be used to emulate an ARM based system to run application software in a production or live environment.
If source code is being provided to the Licensee: use, copy and modify the model for the sole purpose of designing, developing, analyzing, debugging, testing, verifying, validating and optimizing software which: (a) (i) is for ARM based systems; and (ii) does not incorporate the ARM Models or any part thereof; and (b) such ARM Models may not be used to emulate an ARM based system to run application software in a production or live environment.
In the case of any Licensee who is either or both an academic or educational institution the purposes shall be limited to internal use.
Except to the extent that such activity is permitted by applicable law, Licensee shall not reverse engineer, decompile, or disassemble this model. If this model was provided to Licensee in Europe, Licensee shall not reverse engineer, decompile or disassemble the Model for the purposes of error correction.
The License agreement does not entitle Licensee to manufacture in silicon any product based on this model.
The License agreement does not entitle Licensee to use this model for evaluating the validity of any ARM patent.
Source of model available under separate Imperas Software License Agreement.

Limitations

Instruction pipelines are not modeled in any way. All instructions are assumed to complete immediately. This means that instruction barrier instructions (e.g. ISB, CP15ISB) are treated as NOPs, with the exception of any undefined instruction behavior, which is modeled. The model does not implement speculative fetch behavior. The branch cache is not modeled.
Caches and write buffers are not modeled in any way. All loads, fetches and stores complete immediately and in order, and are fully synchronous (as if the memory was of Strongly Ordered or Device-nGnRnE type). Data barrier instructions (e.g. DSB, CP15DSB) are treated as NOPs, with the exception of any undefined instruction behavior, which is modeled. Cache manipulation instructions are implemented as NOPs, with the exception of any undefined instruction behavior, which is modeled.
Real-world timing effects are not modeled: all instructions are assumed to complete in a single cycle.

Verification

Models have been extensively tested by Imperas. ARM7TDMI models have been successfully used by customers to simulate ucLinux on Atmel virtual platforms.

Core Features

Thumb instructions are supported.

Debug Mask

It is possible to enable model debug features in various categories. This can be done statically using the "override_debugMask" parameter, or dynamically using the "debugflags" command. Enabled debug features are specified using a bitmask value, as follows:
Value 0x080: enable debugging of all system register accesses.
Value 0x100: enable debugging of all traps of system register accesses.
Value 0x200: enable verbose debugging of other miscellaneous behavior (for example, the reason why a particular instruction is undefined).
All other bits in the debug bitmask are reserved and must not be set to non-zero values.

AArch32 Unpredictable Behavior

Many AArch32 instruction behaviors are described in the ARM ARM as CONSTRAINED UNPREDICTABLE. This section describes how such situations are handled by this model.

Equal Target Registers

Some instructions allow the specification of two target registers (for example, double-width SMULL, or some VMOV variants), and such instructions are CONSTRAINED UNPREDICTABLE if the same target register is specified in both positions. In this model, such instructions are treated as UNDEFINED.

Floating Point Load/Store Multiple Lists

Instructions that load or store a list of floating point registers (e.g. VSTM, VLDM, VPUSH, VPOP) are CONSTRAINED UNPREDICTABLE if either the uppermost register in the specified range is greater than 32 or (for 64-bit registers) if more than 16 registers are specified. In this model, such instructions are treated as UNDEFINED.

Floating Point VLD[2-4]/VST[2-4] Range Overflow

Instructions that load or store a fixed number of floating point registers (e.g. VST2, VLD2) are CONSTRAINED UNPREDICTABLE if the upper register bound exceeds the number of implemented floating point registers. In this model, these instructions load and store using modulo 32 indexing (consistent with AArch64 instructions with similar behavior).

If-Then (IT) Block Constraints

Where the behavior of an instruction in an if-then (IT) block is described as CONSTRAINED UNPREDICTABLE, this model treats that instruction as UNDEFINED.

Use of R13

In architecture variants before ARMv8, use of R13 was described as CONSTRAINED UNPREDICTABLE in many circumstances. From ARMv8, most of these situations are no longer considered unpredictable. This model allows R13 to be used like any other GPR, consistent with the ARMv8 specification.

Use of R15

Use of R15 is described as CONSTRAINED UNPREDICTABLE in many circumstances. This model allows such use to be configured using the parameter "unpredictableR15" as follows:
Value "undefined": any reference to R15 in such a situation is treated as UNDEFINED;
Value "nop": any reference to R15 in such a situation causes the instruction to be treated as a NOP;
Value "raz_wi": any reference to R15 in such a situation causes the instruction to be treated as a RAZ/WI (that is, R15 is read as zero and write-ignored);
Value "execute": any reference to R15 in such a situation is executed using the current value of R15 on read, and writes to R15 are allowed (but are not interworking).
Value "assert": any reference to R15 in such a situation causes the simulation to halt with an assertion message (allowing any such unpredictable uses to be easily identified).
In this variant, the default value of "unpredictableR15" is "execute".

Unpredictable Instructions in Some Modes

Some instructions are described as CONSTRAINED UNPREDICTABLE in some modes only (for example, MSR accessing SPSR is CONSTRAINED UNPREDICTABLE in User and System modes). This model allows such use to be configured using the parameter "unpredictableModal", which can have values "undefined" or "nop". See the previous section for more information about the meaning of these values.
In this variant, the default value of "unpredictableModal" is "nop".

Integration Support

This model implements a number of non-architectural pseudo-registers and other features to facilitate integration.

Halt Reason Introspection

An artifact register HaltReason can be read to determine the reason or reasons that a processor is halted. This register is a bitfield, with the following encoding: bit 0 indicates the processor has executed a wait-for-event (WFE) instruction; bit 1 indicates the processor has executed a wait-for-interrupt (WFI) instruction; and bit 2 indicates the processor is held in reset.

System Register Access Monitor

If parameter "enableSystemMonitorBus" is True, an artifact 32-bit bus "SystemMonitor" is enabled for each PE. Every system register read or write by that PE is then visible as a read or write on this artifact bus, and can therefore be monitored using callbacks installed in the client environment (use opBusReadMonitorAdd/opBusWriteMonitorAdd or icmAddBusReadCallback/icmAddBusWriteCallback, depending on the client API). The format of the address on the bus is as follows:
bits 31:26 - zero
bit 25 - 1 if AArch64 access, 0 if AArch32 access
bit 24 - 1 if non-secure access, 0 if secure access
bits 23:20 - CRm value
bits 19:16 - CRn value
bits 15:12 - op2 value
bits 11:8 - op1 value
bits 7:4 - op0 value (AArch64) or coprocessor number (AArch32)
bits 3:0 - zero
As an example, to view non-secure writes to writes to CNTFRQ_EL0 in AArch64 state, install a write monitor on address range 0x020e0330:0x020e0333.

System Register Implementation

If parameter "enableSystemBus" is True, an artifact 32-bit bus "System" is enabled for each PE. Slave callbacks installed on this bus can be used to implement modified system register behavior (use opBusSlaveNew or icmMapExternalMemory, depending on the client API). The format of the address on the bus is the same as for the system monitor bus, described above.

Instance Parameters

Several parameters can be specified when a processor is instanced in a platform. For this processor instance 'cpu1' it has been instanced with the following parameters:

Table 3: Processor Instance 'cpu1' Parameters (Configurations)

Table 4: Processor Instance 'cpu1' Parameters (Attributes)

Memory Map for processor 'cpu1' bus: 'bus1'

Processor instance 'cpu1' is connected to bus 'bus1' using master port 'INSTRUCTION'.

Processor instance 'cpu1' is connected to bus 'bus1' using master port 'DATA'.

Table 5: Memory Map ( 'cpu1' / 'bus1' [width: 32] )

Net Connections to processor: 'cpu1'

There are no nets connected to this processor.