Why only Linux uses GCC to compile the source code. please help

Why only Linux uses GCC to compile the source code. please help

[Mahadev K Cholachagudda]

Hi to all,

Please include **** mailto:mahadev_kc@yahoo.com ***** in the reply list
******as i am not a member of the list******.

After i am going through the some part of the linux code, i wrote the
following. Please review it and if you have any additions/modifications or
comments please let me know.

Your help is really needed.

Thanks for any help,

Mahadev K Cholachagudda


The document is as below.

Introduction:

This document describes about the features of gcc which are very much
necessary to compile the Linux and also about the features that an 'x'
compiler does not have if used to compile the Linux.

Details:

1. The GCC has an explicit inline declaration for functions. So this option
may enable the calling function to have the contents of some global
variables in particular register.

2. The GCC has an support for inline assembly with 'C' expression operands
which can be used in 'C' functions.

3. The GCC has a support for including the 'C' header files into the
assembly source files.


The problems if one uses 'x' compiler other than GCC.
=====================================================

1. He/she may not get the features of GCC listed above into the 'x'
compiler.

2. The Linux kernel mainly uses GCC. If the Linux kernel is made to compile
using 'x' compiler other than GCC, then code updation will take time for 'x'
compiler if a newer version or patch of Linux released.

3. The Linux code may have some code which is purely based upon the data
types e.g. for one processor the unsigned long may be 32 bits or 16 bits.




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Re: Why only Linux uses GCC to compile the source code. please help

[Erik Mouw]

On Wed, Jan 24, 2001 at 06:49:13PM +0530, Mahadev K Cholachagudda wrote:
> The problems if one uses 'x' compiler other than GCC.
> =====================================================
> 
> 1. He/she may not get the features of GCC listed above into the 'x'
> compiler.
> 
> 2. The Linux kernel mainly uses GCC. If the Linux kernel is made to compile
> using 'x' compiler other than GCC, then code updation will take time for 'x'
> compiler if a newer version or patch of Linux released.

I see no problems over here. Linux makes explicit use of GCC features,
it was not meant to be compiled with a different compiler. Note that
the Linux kernel is not a normal program, so we don't have to deal with
compatibility. If you want to use another compiler to compile your
kernel: go ahead, but don't expect any help from this list.

> 3. The Linux code may have some code which is purely based upon the data
> types e.g. for one processor the unsigned long may be 32 bits or 16 bits.

That's what the __uXX/__sXX data types are for: to ensure that the data
types are indeed XX bits long. See include/asm-*/types.h.


Erik

-- 
J.A.K. (Erik) Mouw, Information and Communication Theory Group, Department
of Electrical Engineering, Faculty of Information Technology and Systems,
Delft University of Technology, PO BOX 5031,  2600 GA Delft, The Netherlands
Phone: +31-15-2783635  Fax: +31-15-2781843  Email: J.A.K.Mouw@its.tudelft.nl
WWW: http://www-ict.its.tudelft.nl/~erik/