On Thu, Nov 6, 2014 at 6:09 PM, Dimitris Papastamos <s...@2f30.org> 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.
There is the http://llvm.linuxfoundation.org/index.php/Main_Page project that works towards getting the Kernel to compile with clang. That effort should hopefully increase the standards conformance of Kernel code at least somewhat. Cheers, Silvan
