On 2020-03-28 00:13, utkarsh.ra...@gmail.com wrote:
---
user/start/tools.rst | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/user/start/tools.rst b/user/start/tools.rst
index c3f039b..8ea1f64 100644
--- a/user/start/tools.rst
+++ b/user/start/tools.rst
@@ -3,6 +3,7 @@
.. Copyright (C) 2019 embedded brains GmbH
.. Copyright (C) 2019 Sebastian Huber
.. Copyright (C) 2020 Chris Johns
+.. Copyright (C) 2020 Utkarsh Rai
.. _QuickStartTools:
@@ -76,3 +77,36 @@ source code used.
Add ``--verbose`` to the GCC command for the the verbose version details.
+
+
+Need for RTEMS-Specific Cross-Compiler
+--------------------------------------------
Length of ---'s does not match the heading.
+
+New users are often confused as to why they cannot use their distribution's
+cross-compiler for their target on rtems, e.g., the riscv64-linux-gnu or the
+arm-none-eabi-gcc on RTEMS. Below mentioned are some of the reasons for using
+the RTEMS cross-compiler.
+
+ ``Correct configuration of Newlib -``
+ Newlib is a C standard library implementation intended for use on embedded
+ systems. Most of the POSIX and libc support for RTEMS is derived from
+ Newlib. The RTEMS cross-compiler configures Newlib correctly for RTEMS.
+
+ ``Threading in GCC support libraries -``
+ Several threading packages in GCC such as Go threads (libgo), OpenMP
+ (libgomp), and OpenACC need to be customized according to RTEMS. This is
+ done by the RTEMS specific cross-compiler.
+
+ ``Provide preprocessor define __rtems__ -``
+ The ``__rtems__`` preprocessor define is used to provide conditional
code
+ compilation in source files that are shared with other projects e.g. in
+ Newlib or imported code from FreeBSD.
+
+ ``Multilib variants to match the BSP -``
+ RTEMS configures GCC to create separate runtime libraries for each
+ supported instruction set, floating point unit, vector unit, word size
+ (e.g. 32-bit and 64-bit), endianness, ABI, processor errata workarounds,
+ and so on in the architecture. These libraries are termed multilib
variants
+
(https://docs.rtems.org/branches/master/user/hardware/architectures.html?highlight=multilib).
Please do not add external links to internal parts of the same document.
Please use :ref: to do this. A link like this breaks on branches and PDFs.
Chris
+ Multilibs variants to match the BSP are set by selecting a specific set of
+ machine options using the RTEMS cross-compiler.
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