diff options
| -rw-r--r-- | tools/include/nolibc/nolibc.h | 30 |
1 files changed, 20 insertions, 10 deletions
diff --git a/tools/include/nolibc/nolibc.h b/tools/include/nolibc/nolibc.h index 561dcdb83cee..b2bc48d3cfe4 100644 --- a/tools/include/nolibc/nolibc.h +++ b/tools/include/nolibc/nolibc.h @@ -57,22 +57,32 @@ * having to specify anything. * * Finally some very common libc-level functions are provided. It is the case - * for a few functions usually found in string.h, ctype.h, or stdlib.h. Nothing - * is currently provided regarding stdio emulation. + * for a few functions usually found in string.h, ctype.h, or stdlib.h. * - * The macro NOLIBC is always defined, so that it is possible for a program to - * check this macro to know if it is being built against and decide to disable - * some features or simply not to include some standard libc files. - * - * Ideally this file should be split in multiple files for easier long term - * maintenance, but provided as a single file as it is now, it's quite - * convenient to use. Maybe some variations involving a set of includes at the - * top could work. + * The nolibc.h file is only a convenient entry point which includes all other + * files. It also defines the NOLIBC macro, so that it is possible for a + * program to check this macro to know if it is being built against and decide + * to disable some features or simply not to include some standard libc files. * * A simple static executable may be built this way : * $ gcc -fno-asynchronous-unwind-tables -fno-ident -s -Os -nostdlib \ * -static -include nolibc.h -o hello hello.c -lgcc * + * Simple programs meant to be reasonably portable to various libc and using + * only a few common includes, may also be built by simply making the include + * path point to the nolibc directory: + * $ gcc -fno-asynchronous-unwind-tables -fno-ident -s -Os -nostdlib \ + * -I../nolibc -o hello hello.c -lgcc + * + * The available standard (but limited) include files are: + * ctype.h, errno.h, signal.h, stdio.h, stdlib.h, string.h, time.h + * + * In addition, the following ones are expected to be provided by the compiler: + * float.h, stdarg.h, stddef.h + * + * The following ones which are part to the C standard are not provided: + * assert.h, locale.h, math.h, setjmp.h, limits.h + * * A very useful calling convention table may be found here : * http://man7.org/linux/man-pages/man2/syscall.2.html * |