星载处理器

The European Space Agency’s ERC32 is a microprocessor implementing a SPARC V7 processor and associated support circuitry for embedded space applications. The integer and floating-point units (90C601E & 90C602E) are based on the Cypress 7C601 and 7C602, with additional error-detection and recovery functions.

The ERC32 is available from Atmel as the TSC695F.

http://www.esa.int/Our_Activities/Space_Engineering_Technology/Onboard_Computer_and_Data_Handling/Microprocessors

The LEON2 is a synthesisable VHDL model of a 32-bit processor conforming to the IEEE-1754 (SPARC V8) architecture.

The LEON2 is based on an AMBA AHB/APB bus architecture, so new modules can easily be added to extend its functionality.

Advanced Microcontroller Bus Architecture. AMBA was introduced by ARM in 1996. The first AMBA buses were Advanced System Bus (ASB) and Advanced Peripheral Bus (APB). In its second version, AMBA 2 in 1999, ARM added AMBA High-performance Bus (AHB) that is a single clock-edge protocol.

The LEON2-FT design is an extension of the basic LEON2 model including advanced fault-tolerance features to withstand arbitrary single-event upset (SEU) errors without loss of data. The fault-tolerance is provided at design (VHDL) level, and does not require an SEU-hard semiconductor process, nor a custom cell library or special back-end tools. Atmel has manufactured an ASIC version of the LEON2-FT in the ATH18RHA rad hard process, available through their catalogue as part number AT697F.

Microchip已经收购Atmel，Mircochip的单片机为PIC，Atmel的单片机为AVR，两者结合为了更好的应对ARM的竞争。

April 4, 2016 – Microchip Technology Incorporated (NASDAQ: MCHP), a leading provider of microcontroller, mixed-signal, analog and flash-IP solutions, today announced that it has completed its acquisition of Atmel Corporation.

Microchip/Atmel have the theopportunity to combine the best of the AVR and PIC worlds into an awesomemicrocontroller platform. Despite the growing popularity and decreasingcost of powerful 32-bit ARM chips, there are still plenty of applicationswhere 8 bits are all you need.

The LEON3 is a synthesisable VHDL model of a 32-bit processor compliant with the IEEE-1754 (SPARC V8) architecture. The LEON3 is an extension to the LEON2 processor, featuring a 7-stage pipeline (vs the 5-stage pipeline of the LEON2), and supporting both asymmetric and symmetric multiprocessing (AMP/SMP). Up to 16 CPU can be used in a multiprocessing configuration. 多核

The LEON4 is the latest implementation of the SPARC V8 architecture by Aeroflex Gaisler, in the form of a synthesizable VHDL model of a 32-bit microprocessor. As was the case with the previous LEON models, the LEON4 is also highly configurable, and particularly suitable for system-on-chip (SoC) designs. The LEON4 extends the LEON3 model with support for an optional Level-2 (L2) cache, a pipeline with 64-bit internal load/store data paths, and an AMBA interface of either 64- or 128-bits. Branch prediction, 1-cycle load latency and a 32x32 multiplier results in a performance of 1.7 DMIPS/MHz, or 2.1 CoreMark/MHz.

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从高级语言到二进制机器语言的接口？

下面介绍来自于RTEMS网站，https://docs.rtems.org/branches/master/cpu-supplement/sparc.html

Each high-level language compiler generates subroutine entry and exit code based upon a set of rules known as the application binary interface (ABI) calling convention. These rules address the following issues:

• register preservation and usage
• parameter passing
• call and return mechanism

An ABI calling convention is of importance when interfacing to subroutines written in another language either assembly or high-level. It determines also the set of registers to be saved or restored during a context switch and interrupt processing.

The ABI relevant for RTEMS on SPARC is defined by SYSTEM V APPLICATION BINARY INTERFACE, SPARC Processor Supplement, Third Edition.

SYSTEM V APPLICATION BINARY INTERFACE-3.1

SYSTEM V APPLICATION BINARY INTERFACE, SPARC Processor Supplement, Third Edition

链接：https://pan.baidu.com/s/1lRCz7Z0nol-8gOzed3Rmyw
提取码：0kjr

交叉编译

https://wiki.osdev.org/GCC_Cross-Compiler

Generally speaking, a cross-compiler is a compiler that runs on platform A (the host), but generates executables for platform B (the target). These two platforms may (but do not need to) differ in CPU, operating system, and/or executable format.

制作交叉编译的gcc，binutils。通常使用sparc-elf-gcc，生成ELF文件。

https://wiki.osdev.org/GCC_Cross-Compiler

ELF格式介绍

https://wiki.osdev.org/ELF

GNU linker, the ld

可以通过-o选项设置输出文件的名称，如果不指定，则默认输出a.out。

也可以通过--oformat选项（或通过脚本的OUTPUT_FORMAT）指定输出文件的格式，都有哪些格式可以指定呢？如果不指定的话，默认是什么格式呢？

可以用objdump -i来显示支持的二进制格式。.out和.exe文件。

-o output``--output=outputUse output as the name for the program produced by ld; if this option is not specified, the name `a.out' is used by default. The script command OUTPUT can also specify the output file name.

--oformat output-format``ld may be configured to support more than one kind of object file. If your ld is configured this way, you can use the `--oformat' option to specify the binary format for the output object file. Even when ld is configured to support alternative object formats, you don't usually need to specify this, as ld should be configured to produce as a default output format the most usual format on each machine. output-format is a text string, the name of a particular format supported by the BFD libraries. (You can list the available binary formats with `objdump -i'.) The script command OUTPUT_FORMAT can also specify the output format, but this option overrides it. See section BFD.

UNIX最初使用out格式，后来，使用COFF格式，再后来，使用ELF格式。

out，只有3个段加1个符号表和1个字符串表；

COFF，包含一个段表，因此，可以包含不止3个段；

ELF，支持多个段。

out format for the PDP-7, similar to the a.out format used on the PDP-11, appeared in the first edition of UNIX. It was superseded by the COFF format in AT&T Unix System V, which was in turn superseded by the ELF format in System V Release 4 .

• a.out

  The oldest and `classic' unix object format. It uses a short and compact header with a magic number at the beginning that's often used to characterize the format (see a.out(5) for more details). It contains three loaded segments: .text, .data, and .bss plus a symbol table and a string table.

• COFF

  The SVR3 object format. The header now comprises a section table, so you can have more than just .text, .data, and .bss sections.

• ELF

  The successor to COFF, featuring Multiple sections and 32-bit or 64-bit possible values. One major drawback: ELF was also designed with the assumption that there would be only one ABI per system architecture. That assumption is actually quite incorrect, and not even in the commercial SYSV world (which has at least three ABIs: SVR4, Solaris, SCO) does it hold true.

ELF文件里有program header和section header

前者包含各种段segment的信息，比如text data等，这些在链接前和后都存在，用于约定每个段应该在内存的什么位置。

后者包含链接信息，用于链接时使用，链接后就没有了。

是不是可以用readelf查看可重定位文件o文件和可执行文件exe文件，确定每个文件里包含的信息，确认是否可执行文件里没有section信息，只有segment信息。

bin文件又是什么关系呢？