[U-Boot] m68k: Build problems on some boards

Angelo Dureghello angelo at sysam.it
Mon Dec 22 19:06:51 CET 2014

Dear Masahiro,

On 15/12/2014 17:46, Masahiro YAMADA wrote:

> This is a known (and unfortunate) problem.
> The Linux m68k toolchains (as I am using) define size_t as "unsigned
> int", whereas bare-metal m68k toolchains (as you are using) define
> size_t as "unsigned long".
> People often want to adjust the type definition to the toolchains they
> are using.
> Commit ddc94378d changed __kernel_size_t definition from "unsigned
> int" to "unsigned long".
> Commit fbe79a17 changed it back to "unsigned int" again.
> BTW, Linux Kernel has the same problem as we have for U-Boot.
> I posted a question about this to LKML.
> If you are interested in it, check out this thread:
> https://lkml.org/lkml/2014/12/15/110
> According to that thread, the solution the kernel folks chose
> is to always use toolchains configured for Linux.
> For U-Boot, I think we have two options
> [1] Follow the Linux's way:
>     Ban bare-metal toolchains and always use kernel.org ones
> [2] Use __SIZE_TYPE__ (or include <stddef.h>)
>       to support both types of toolchains.
Many thanks for the deep analysis and clarifications.

For me, it is good we know [1] is compiling properly, so i am fine
to adopt the kernel.org 32/64 bit toolchains for m68k development,
if the community agree, i can prepare a u.boot m68k wiki page with
this information.

The discussion for [2] is interesting to me, i am trying to understand
the thing properly but i still have some doubts: from my understanding,
a bare-metal toolchain should be without libc support (or minimal), so
the kernel.org "nolibc" should be considered bare-metal ? If so, could
the issue be related to "certain" toolchain only ?

Also, i am not understanding, i am comparing now 2 different toolchains:

/MAKEALL -a m68k
compiles with warning: format '%zx' expects argument of type 'size_t', 
but argument 4 has type 'unsigned int' [-Wformat]

./MAKEALL -a m68k
this compiles fine, no warnings

But if i look to the <stddef.h> of the 2 toolchains, they are exactly
the same. So why the compilers expects different definitions of
size_t ?

Angelo Dureghello

Option [2] would be better of course, could the change to use
__SIZE_TYPE__ (or include <stddef.h>) be done in a single place ? What
impact it can have for other architectures then ?

We can also simply collect in a wiki page for m68k dev this informations,
(to use kernel.org, and explain the warning reason).

Best Regards
Angelo Dureghello

> Best Regards
> Masahiro Yamada

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