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Re: [PATCH] uapi: fix asm/signal.h userspace compilation errors

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On Thu, Mar 02, 2017 at 10:22:18AM -0500, Carlos O'Donell wrote:
> On Wed, Mar 1, 2017 at 11:20 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> > On Sun, Feb 26, 2017 at 2:01 AM, Dmitry V. Levin <ldv@altlinux.org> wrote:
> >> Include <stddef.h> (guarded by #ifndef __KERNEL__) to fix asm/signal.h
> >> userspace compilation errors like this:
> >>
> >> /usr/include/asm/signal.h:126:2: error: unknown type name 'size_t'
> >>   size_t ss_size;
> >>
> >> As no uapi header provides a definition of size_t, inclusion
> >> of <stddef.h> seems to be the most conservative fix available.
[...]
> > I'm not sure if this is the best fix. We generally should not include one
> > standard header from another standard header. Would it be possible
> > to use __kernel_size_t instead of size_t?
> 
> In glibc we handle this with special use of __need_size_t with GCC's
> provided stddef.h.
> 
> For example glibc's signal.h does this:
> 
> # define __need_size_t
> # include <stddef.h>

Just to make it clear, do you suggest this approach for asm/signal.h as well?

[...]
> Changing the fundamental type causes the issues you see in patch v2
> where sizeof(size_t) < sizeof(__kernel_size_t).
> 
> It will only lead to problem substituting the wrong type.

I don't see any appetite for creating more ABIs like x32 with
sizeof(size_t) < sizeof(__kernel_size_t), so v2 approach
is not going to be any different from v1 in maintenance.


-- 
ldv

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Re: [PATCH] uapi: fix asm/signal.h userspace compilation errors Arnd Bergmann <arnd@arndb.de> - 2017-03-01 17:30 +0100
  [PATCH v2] x86/uapi: fix asm/signal.h userspace compilation error "Dmitry V. Levin" <ldv@altlinux.org> - 2017-03-02 01:20 +0100
    Re: [PATCH v2] x86/uapi: fix asm/signal.h userspace compilation error hpa@zytor.com - 2017-03-02 01:30 +0100
      Re: [PATCH v2] x86/uapi: fix asm/signal.h userspace compilation error "Dmitry V. Levin" <ldv@altlinux.org> - 2017-03-02 02:30 +0100
        [PATCH v3 2/2] x86/uapi: fix asm/signal.h userspace compilation error "Dmitry V. Levin" <ldv@altlinux.org> - 2017-03-03 02:50 +0100
        [PATCH 1/2] uapi: introduce __kernel_uapi_size_t "Dmitry V. Levin" <ldv@altlinux.org> - 2017-03-03 02:50 +0100
  [PATCH v2] uapi: fix asm/signal.h userspace compilation errors "Dmitry V. Levin" <ldv@altlinux.org> - 2017-03-02 01:30 +0100
  Re: [PATCH] uapi: fix asm/signal.h userspace compilation errors "Carlos O'Donell" <carlos@systemhalted.org> - 2017-03-02 16:30 +0100
    Re: [PATCH] uapi: fix asm/signal.h userspace compilation errors "Dmitry V. Levin" <ldv@altlinux.org> - 2017-03-02 17:10 +0100
      Re: [PATCH] uapi: fix asm/signal.h userspace compilation errors "Carlos O'Donell" <carlos@systemhalted.org> - 2017-03-04 02:30 +0100
        Re: [PATCH] uapi: fix asm/signal.h userspace compilation errors "Carlos O'Donell" <carlos@systemhalted.org> - 2017-03-06 16:20 +0100

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