Date: Sun, 19 Nov 2006 09:25:07 -0500
From: Jeff Dike <jdike@addtoit.com>
To: Olaf Hering <olaf@aepfle.de>
Cc: linux-kernel@vger.kernel.org
Subject: Re: uml fails to compile due to missing offsetof
Message-ID: <20061119142507.GA3284@ccure.user-mode-linux.org>
References: <20061119120000.GA4926@aepfle.de>
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On Sun, Nov 19, 2006 at 01:00:01PM +0100, Olaf Hering wrote:
> 
> I fail to see how arch/um/sys-i386/user-offsets.c can compile since
> offsetof() was declared __KERNEL__ only in include/linux/stddef.h.
> Does it work for anyone else? 

It obviously works for me.  offsetof is very standard C.  I'd venture
to say that a system which can't find it has a broken gcc installation.

> If so, is linux/stddef.h or /usr/include/linux/stddef.h used during
> compilation?

/usr/include/linux/stddef.h (but see below) - this is a userspace
file, so it builds against libc headers.

> The x86_64 variant looks weird as well, linux/stddef.h is appearently
> included via some other headers.

Well, /usr/include/linux/stddef.h on my x86_64 box has no offsetof,
despite being FC5 just like my i386 laptop.  Yay for consistency.

However, there is a /usr/lib/gcc/x86_64-redhat-linux/4.1.1/include/stddef.h
which defines offsetof (and there's a corresponding file on my
laptop), so I bet that's the true source of offsetof.

				Jeff
-- 
Work email - jdike at linux dot intel dot com
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