[U-Boot] [PATCH 1/7] types.h: define (u)int8_t, (u)int16_t, (u)int32_t based on compiler info (MAD)

[Simon Glass]

Hi Masahiro,

On 22 December 2014 at 03:15, Masahiro Yamada <yamada.m at jp.panasonic.com> wrote:
> The intent of this series is to show the nasty problems introduced
> by <stdint.h>.
>
> Simon and I are already discussing this in the following thread:
> http://thread.gmane.org/gmane.comp.boot-loaders.u-boot/203954
> http://thread.gmane.org/gmane.comp.boot-loaders.u-boot/198550/focus=205880

I'll reply on that thread but I will add a few comments on each patch as well.

>
>    -----
>
> Commit 0d296cc2d3b8 (Provide option to avoid defining a custom version
> of uintptr_t.) introduced CONFIG_USE_STDINT.  If it is enabled,
> <stdint.h> is included and uint64_t, u_int64_t, int64_t are defined
> based on the compiler-provided information.  While, inconsistently,
> that commit left uint_{8,16,32}_t, u_int{8,16,32}t, int_{8,16,32}t
> to be hard-coded in include/linux/types.h.
>
> This causes type conflicts between the typedefs defined in the compiler's
> <stdint.h> and the ones hard-coded in include/linux/types.h.
>
> As you may know, 'uint32_t' is defined as 'unsigned long' in some compilers
> such as bare metal ARM toolchain, whereas it is defined as 'unsigned int'
> in kernel.org ones.
> (This is also clearly mentioned in Linux's arch/arm/include/asm/types.h)

In that file, it actually redefines the types so that stdint.h can be
included. Are you suggesting that we should follow the same route?

That suggests that Gabe's implementation is not correct, but not that
the whole concept is wrong.

 * As the typedefs for these types in 'stdint.h' are based on builtin defines
 * supplied by GCC, we can tweak these to align with the kernel's idea of those
 * types, so 'linux/types.h' and 'stdint.h' can be safely included from the same
 * source file (provided that -ffreestanding is used).

>
> If you make a decision to use a compiler-provided <stdint.h>,
> we cannot hard-code the fixed-width types.
> To avoid the type conflicts, we must make all of them compiler-dependent
> consistently.
>
> You can reproduce this problem, for example, with a Linaro toolchain.
>
> Visit "http://www.linaro.org/downloads/" and download "Bare-metal toolchain
> for Cortex-R/M and Cortex-A".
>
> $ make USE_STDINT=1 CROSS_COMPILE=arm-none-eabi- omap4_panda_defconfig all
>   HOSTCC  scripts/basic/fixdep
>   HOSTCC  scripts/kconfig/conf.o
>    [snip]
>   CC      lib/asm-offsets.s
> In file included from /opt/gcc-arm-none-eabi-4_7-2013q1/bin/../lib/gcc/arm-none-eabi/4.7.3/include/stdint.h:5:0,
>                  from include/compiler.h:117,
>                  from include/image.h:19,
>                  from include/common.h:82,
>                  from lib/asm-offsets.c:15:
> /opt/gcc-arm-none-eabi-4_7-2013q1/bin/../lib/gcc/arm-none-eabi/4.7.3/include/stdint-gcc.h:40:24: error: conflicting types for 'int32_t'
> In file included from include/common.h:21:0,
>                  from lib/asm-offsets.c:15:
> include/linux/types.h:99:17: note: previous declaration of 'int32_t' was here
> In file included from /opt/gcc-arm-none-eabi-4_7-2013q1/bin/../lib/gcc/arm-none-eabi/4.7.3/include/stdint.h:5:0,
>                  from include/compiler.h:117,
>                  from include/image.h:19,
>                  from include/common.h:82,
>                  from lib/asm-offsets.c:15:
> /opt/gcc-arm-none-eabi-4_7-2013q1/bin/../lib/gcc/arm-none-eabi/4.7.3/include/stdint-gcc.h:52:25: error: conflicting types for 'uint32_t'
> In file included from include/common.h:21:0,
>                  from lib/asm-offsets.c:15:
> include/linux/types.h:105:17: note: previous declaration of 'uint32_t' was here

I suspect I have not tested this toolchain, so have not see this
problem. Perhaps this compiler cannot support stdint.h?

In any case I don't think it is necessary to fiddle with the 8, 16,
32-bit types, so this patch is not needed.

>
> Signed-off-by: Masahiro Yamada <yamada.m at jp.panasonic.com>
> Cc: Gabe Black <gabeblack at chromium.org>
> Cc: Simon Glass <sjg at chromium.org>
> Cc: Bill Richardson <wfrichar at google.com>
> Cc: Tom Rini <trini at ti.com>
> ---
>
>  include/linux/types.h | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
>
> diff --git a/include/linux/types.h b/include/linux/types.h
> index c9a8d9a..5549479 100644
> --- a/include/linux/types.h
> +++ b/include/linux/types.h
> @@ -91,18 +91,33 @@ typedef unsigned long               ulong;
>  #ifndef __BIT_TYPES_DEFINED__
>  #define __BIT_TYPES_DEFINED__
>
> +#if defined(CONFIG_USE_STDINT)
> +typedef                __UINT8_TYPE__  u_int8_t;
> +typedef                __INT8_TYPE__   int8_t;
> +typedef                __UINT16_TYPE__ u_int16_t;
> +typedef                __INT16_TYPE__  int16_t;
> +typedef                __UINT32_TYPE__ u_int32_t;
> +typedef                __INT32_TYPE__  int32_t;
> +#else
>  typedef                __u8            u_int8_t;
>  typedef                __s8            int8_t;
>  typedef                __u16           u_int16_t;
>  typedef                __s16           int16_t;
>  typedef                __u32           u_int32_t;
>  typedef                __s32           int32_t;
> +#endif
>
>  #endif /* !(__BIT_TYPES_DEFINED__) */
>
> +#if defined(CONFIG_USE_STDINT)
> +typedef                __UINT8_TYPE__  uint8_t;
> +typedef                __UINT16_TYPE__ uint16_t;
> +typedef                __UINT32_TYPE__ uint32_t;
> +#else
>  typedef                __u8            uint8_t;
>  typedef                __u16           uint16_t;
>  typedef                __u32           uint32_t;
> +#endif
>
>  #if defined(__GNUC__) && !defined(__STRICT_ANSI__) && \
>         (!defined(CONFIG_USE_STDINT) || !defined(__INT64_TYPE__))
> --
> 1.9.1
>

Regards,
Simon