On Thu, Nov 06, 2014 at 05:09:44PM +0000, Dimitris Papastamos wrote:
> On Thu, Nov 06, 2014 at 05:56:55PM +0100, Sylvain BERTRAND wrote:
> > On Thu, Nov 06, 2014 at 03:40:56PM +0000, Dimitris Papastamos wrote:
> > > On Thu, Nov 06, 2014 at 04:38:20PM +0100, Sylvain BERTRAND wrote:
> > > > On a personnal level, I port some of my C99 projects back to C89, since
> > > > it
> > > > seems a C89 compiler is easier to write than a C99 compiler, and some
> > > > part of
> > > > my code could go in C89 only project (i.e. the linux kernel).
> > >
> > > the linux kernel is built with gnu99 iirc.
> >
> > Documentation/HOWTO:
> > "The kernel is written using GNU C and the GNU toolchain. While it
> > adheres to the ISO C89 standard, it uses a number of extensions that are
> > not featured in the standard. The kernel is a freestanding C
> > environment, with no reliance on the standard C library, so some
> > portions of the C standard are not supported. Arbitrary long long
> > divisions and floating point are not allowed. It can sometimes be
> > difficult to understand the assumptions the kernel has on the toolchain
> > and the extensions that it uses, and unfortunately there is no
> > definitive reference for them. Please check the gcc info pages (`info
> > gcc`) for some information on them."
>
> It uses a *lot* of extensions. If I remember correctly, a significant number
> of gcc extensions were initially driven by the needs of linux kernel
> programmers.
>
> A C89 only compiler would have no hope to build the kernel in any way
> so I do not see how C89 is relevant here anymore.
1 - because it's easier to port to C89/C90 + gnu extensions from C89/C90 than
C99 (moving variable declarations back at the beginning of each block is
already a pain)
2 - this is related to what I'm doing to my code, it was informational in order
to help you do your choice.
regards,
--
Sylvain
